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P1 08 Communications WavesMr Powell
371 minutes
371 marks
Q1. (a) The new Tetra communications system to be used by the police transmits digital signals using microwaves of wavelength 75 cm.
(i) Use the following equation to calculate the frequency of the microwaves used by the Tetra system. Show clearly how you work out your answer.
wave speed = frequency × wavelength
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Frequency = ......................................... hertz(2)
(b) Read the following extract from a newspaper and then answer the questions that follow.
Residents of Stag Hill Court, a luxury block of flats, are shocked at the plans to site a mobile phone mast on the roof of the flats. They oppose the mast on health grounds, quoting research in Germany that has found a possible increase in cases of cancer around mobile phone masts.
A spokesperson for the telecoms company said, ‘The residents should not worry. The research carried out by our own scientists has found no link between ill health and mobile phone masts’.
This has not reassured the residents, who argue that new independent research is urgently needed.
(i) Explain why living near a mobile phone mast could cause ill health.
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(ii) Suggest two reasons why the residents have not been reassured by the research carried out by the telecoms company.
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2 ........................................................................................................................
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(Total 7 marks)
Q2. (a) The new Tetra communications system to be used by the police transmits digital signals using microwaves of wavelength 75 cm.
(i) Use the following equation to calculate the frequency of the microwaves used by the Tetra system. Show clearly how you work out your answer.
wave speed = frequency × wavelength
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Frequency = ......................................... hertz(2)
(b) Read the following extract from a newspaper and then answer the questions that follow.
Residents of Stag Hill Court, a luxury block of flats, are shocked at the plans to site a mobile phone mast on the roof of the flats. They oppose the mast on health grounds, quoting research in Germany that has found a possible increase in cases of cancer around mobile phone masts.
A spokesperson for the telecoms company said, ‘The residents should not worry. The research carried out by our own scientists has found no link
between ill health and mobile phone masts’.
This has not reassured the residents, who argue that new independent research is urgently needed.
(i) Explain why living near a mobile phone mast could cause ill health.
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(ii) Suggest two reasons why the residents have not been reassured by the research carried out by the telecoms company.
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2 ........................................................................................................................
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(Total 7 marks)
Q3. (a) A student listens to the sound waves produced by a car siren. When the car is stationary, the student hears a constant frequency sound.
Describe how the wavelength and frequency of the sound waves heard by the student change when the car is driven away from the student.
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(b) Satellites fitted with various telescopes orbit the Earth. These telescopes detect different types of electromagnetic radiation.
Why are telescopes that detect different types of electromagnetic waves used to observe the Universe?
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(c) In 2005 a space telescope detected a star that exploded 13 billion years ago. The light from the star shows the biggest red-shift ever measured.
(i) What is red-shift?
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(ii) What does the measurement of its red-shift tell scientists about this star?
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(d) Red-shift provides evidence for the ‘big bang’ theory.
(i) Describe the ‘big bang’ theory.
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(ii) Suggest what scientists should do if new evidence were found that did not support the ‘big bang’ theory.
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(Total 8 marks)
Q4. The diagram represents part of the electromagnetic spectrum.
(i) Visible light travels through air at 300 000 000 m/s.
Why can we assume that radio waves travel through air at the same speed as light?
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(ii) A radio station broadcasts at a frequency of 200 kHz.
Use the following equation to calculate the wavelength of the waves broadcast by this radio station. Show clearly how you work out your answer.
wave speed = frequency × wavelength
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Wavelength = ……………. m(2)
(iii) Draw a vertical line on the diagram above to show the position of this radio wave in the electromagnetic spectrum.
(1)(Total 4 marks)
Q5. (a) Mobile phones send digital signals using electromagnetic waves.
(i) Which one of the following types of electromagnetic wave is used to carry information between masts in a mobile phone network?
Draw a ring around your answer.
light microwave radio(1)
(b) Some people worry that using a mobile phone may be bad for their health.
Look at this information taken from a recent newspaper article.
• Scientists in Sweden found that the regular use of a mobile phone increases the risk of a cancerous growth between the ear and the brain.
• Some people who use mobile phones for a long time complain of headaches and tiredness. The same effect has not been noticed in laboratory tests.
• There is no reliable evidence to link using mobile phones with ill health.
• The waves from a mobile phone are not strong enough to cause long-term heat damage to cells in the body.
(i) Complete the following sentence by drawing a ring around the word in the box that is correct.
The evidence from different scientists doing the same investigation is reliable if
all the scientists get
different
identical
random
results.
(1)
(ii) What information in the article supports the idea that mobile phones are bad for your health?
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(iii) Some scientists say that using a mobile phone is totally safe.
What information in the article supports this view?
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(Total 6 marks)
Q6. The diagram shows a small part of the electromagnetic spectrum divided into seven sections.
The different properties of the waves in each section make them useful in different ways.
The waves in which section, A, B, C, D, E, F or G, are:
(a) used to send a signal to a satellite in space
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(b) used to communicate with a submarine under the water
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(c) used by a radio station to broadcast programmes around the world
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(d) the waves with the shortest wavelength?
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(Total 4 marks)
Q7. When sound waves reach a material, some of the energy of the sound is reflected and some
is transmitted through the material.
(a) Complete the sentence.
Sound waves are caused by ........................................................................................(1)
(b) The graphs J, K, L and M represent the sound energy reflected from a surface.
The graphs are all drawn to the same scale.
Which graph shows the greatest total sound energy output from the surface?
Graph ....................................................(1)
(c) The proportion of the sound energy which is reflected or transmitteddepends on the material which receives the sound.
A student investigates different materials.
The diagram shows how a student sets up her equipment.
(i) Using a pencil and ruler to draw on the diagram, show how microphone X receives reflected sound.
(2)
(ii) The student tests four materials. Each sheet of material is 1 mm thick. This has been glued onto a block of expanded polystyrene.
Why does the student use the same size of expanded polystyrene block and thesame sound level for each test?
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(iii) The table shows the readings for the sound level transmitted to microphone Y.
Sound level fromloudspeaker inarbitrary units
SurfacematerialSound level transmitted tomicrophone Y in arbitraryunits
60 paper 39
60 plaster 18
60 cloth 31
60 wood 15
[A] Which surface material transmits the smallest proportion of the sound?
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[B] What proportion is this?
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(1)
(d) People living in a flat have very noisy neighbours who are always playing loud music.
Suggest one practical idea to reduce the amount of noise transmitted into the flat through the walls and explain how your idea will work.
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(Total 9 marks)
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(a) The wavelengths of four different types of electromagnetic wave, including visible light waves, are given in the table.
Type of wave Wavelength
Visible light 0.0005 mm
A 1.1 km
B 100 mm
C 0.18 mm
Which of the waves, A, B or C, is an infra red wave? ....................................(1)
(b) A TV station broadcasts at 500 000 kHz. The waves travel through the air at300 000 000 m/s.
Use the equation in the box to calculate the wavelength of the waves broadcast by this station.
wave speed = frequency × wavelength
Show clearly how you work out your answer.
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Wavelength = .............................. m(2)
(c) What happens when a metal aerial absorbs radio waves?
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(d) Stars emit all types of electromagnetic waves. Telescopes that monitor X-rays are mounted on satellites in space.
Why would an X-ray telescope based on Earth not be able to detect X-rays emitted from distant stars?
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(Total 6 marks)
Q9. A student uses a ray box and a semicircular glass block to investigate refraction.
(a) What is the vertical dashed line called?
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(b) Which angle, v, w, x, y or z, is the angle of refraction?
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(c) Why has refraction taken place?
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(d) In an investigation, a student always aims the light from the ray box at point P.She moves the ray box to give different values of angle v.She records angle y for each of these values. The table shows her results.
Angle vmeasured in degrees
Angle ymeasured in degrees
30 19
40 25
50 31
60 35
70 39
80 41
The student studies the data and comes to the following conclusion.
Angle y is directly proportional to angle v.
Her friend says that this conclusion is not correct.
(i) Use data from the table to explain why the conclusion is not correct.
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(ii) Write a correct conclusion for the experiment.
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(iii) Why is your conclusion only valid when angle v is between 30° and 80°?
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(Total 7 marks)
Q10. In the diagram below, a frog sits on a rock in a pond.
(a) Complete the following sentences by drawing a ring around the correct line in the box.
(i) The frog can see its image in the pond because the surface of the pond acts
like a
concave
convex
plane
mirror.
(1)
(ii) Draw a ring around each of two words from the box below to describe the image in the pond.
bigger inverted real smaller upright virtual(2)
(b) There is an insect underneath the rock.
Use a ruler to draw rays of light on the diagram to show how the frog uses reflection tosee the insect.
Mark the direction of the rays.
(3)
(Total 6 marks)
Q11. (a) A student uses two pieces of equipment, A and B, to display a sound wave.
(i) Use words from the box to complete the sentence.
a loudspeaker a microphone an oscilloscope a screen
A is ............................................ and B is ....................................................... .(2)
(ii) Use words from the box to complete the sentence.
the amplitude half the amplitude the frequency half the frequency
The distance x marked on the diagram measures ......................................... of the sound wave.
(1)
(iii) Complete the sentence.
The distance x becomes smaller. This is because the sound has
become ............................................................................................................ .(1)
(b) There is no air in space.
Astronauts in space cannot hear sounds from outside their spacesuits.
Explain this.
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(Total 6 marks)
Q12. (a) Some scientists think that there is a link between using a mobile phone and some types of illness. Other scientists disagree. They say that the evidence is limited andunreliable.
(i) Suggest what scientists could do to show a link between using a mobile phone and illness.
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(ii) How could scientists improve the reliability of the evidence?
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(iii) Complete the following passage by drawing a ring around the word in the box that is correct.
There has been little or no experimental research into the health of children who use mobile phones.
This is partly because of the
economic
environmental
ethical
issues involved in using
children in scientific research.(1)
(b) Before being sold, new mobile phones must be tested and given a SAR value.The SAR value is a measure of the energy absorbed by the head while a mobile phone is being used.
The table gives the SAR value for three mobile phones made by different companies.To be sold in the UK, a mobile phone must have a SAR value lower than 2.0 W/kg.
Mobile phone SAR value in W/kg
J 0.18
K 0.86
L 1.40
(i) All companies use the same test to measure a SAR value.
Why is using the same test important?
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(ii) Would the companies that make the mobile phones, J, K and L, be correct to claim that these three phones are totally safe to use?
Answer yes or no. ..............................
Give a reason for your answer.
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(c) Devices designed to protect a mobile phone user from microwave radiation are now available.
Why is it important that these devices are tested by scientists who are not working for the company that makes the devices?
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(Total 6 marks)
Q13. A puppy can see an image of himself in a plane mirror.
The diagram shows how the puppy can see his disc.
(a) On the diagram, use a ruler to draw a ray to show how the puppy can see the top of his ear, which is marked as T.
(3)
(b) What is a plane mirror?
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(Total 4 marks)
Q14. A microphone and a cathode ray oscilloscope (CRO) can be used to show the pattern of a sound wave.
Four sound wave patterns, A, B, C and D, are shown.
They are all drawn to the same scale.
(a) Which one of the patterns has the smallest amplitude? .....................................................
(b) Which one of the patterns has the lowest frequency? ........................................................(Total 2 marks)
Q15. (a) Microwaves are one type of electromagnetic wave.
(i) Which type of electromagnetic wave has a lower frequency than microwaves?
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(ii) What do all types of electromagnetic wave transfer from one place to another?
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(b) The picture shows a tennis coach using a speed gun to measure how fast the player serves the ball.
(i) The microwaves transmitted by the speed gun have a frequency of 24 000 000 000 Hz and travel through the air at 300 000 000 m/s.
Use the equation in the box to calculate the wavelength of the microwaves emitted
from the speed gun.
wave speed = frequency × wavelength
Show clearly how you work out your answer.
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Wavelength = .............................. m(2)
(ii) Some of the microwaves transmitted by the speed gun are absorbed by the ball.
What effect will the absorbed microwaves have on the ball?
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(iii) Some of the microwaves transmitted by the speed gun are reflected from the moving ball back towards the speed gun.
Describe how the wavelength and frequency of the microwaves change as they are reflected from the moving ball.
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(Total 7 marks)
Q16. (a) The picture shows a speed gun being used to measure how fast a tennis player hits the ball.
Some of the microwaves from the speed gun are absorbed by the ball and some are reflected by the ball.
(i) Complete the following sentence by choosing one of the phrases from the box.
longer than the same as shorter than
The wavelength of the microwaves reflected from the ball are
................................................................... the wavelength of the microwaves
from the speed gun.(1)
(ii) Complete the following sentence by drawing a ring around the correct line in the box.
decrease slightly
When the ball absorbs microwaves, its temperature will not change
increase slightly
(1)
(b) The microwaves reflected from the ball have a higher frequency than the microwaves from the speed gun.The graph shows how the difference between the two frequencies depends on the speed of the ball.
(i) Describe the pattern that links the difference between the two frequencies and the speed of the ball.
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(ii) The speed gun measures the difference between the two frequencies as 3200 Hz.
Use the graph to find the speed of the tennis ball.Show clearly on the graph how you obtain your answer.
Speed of the tennis ball = .............................. m/s(2)
(iii) Which one of the following gives the reason why the data has been shown as a line graph and not as a bar chart?
Put a tick ( ) in the box next to your choice.
Frequency and speed are both categoric variables.
Frequency and speed are both continuous variables.
Speed is a continuous variable and frequency is a categoric variable. (1)
(Total 6 marks)
Q17. The table shows the electromagnetic spectrum.Three types of wave have been missed out.
(i) Use words from the box to complete the table.
infra red rays radio waves X-rays(2)
(ii) Which one of the following gives a use of gamma rays?
Put a tick ( ) in the box next to your choice.
to communicate with satellites
to see objects
to kill cancer cells
(1)
(iii) Complete the following sentence by drawing a ring around the correct word in the box.
energy
All electromagnetic waves move
gases from one place to another.
particles
(1)(Total 4 marks)
Q18.(a) A pendulum is a device that can be used for timing. Some clocks rely on the swing of a pendulum to keep time.The pendulum shown in the diagram below is suspended from point Y and swings from Ato B, through the centre point Z.
The displacement x of the pendulum bob was plotted against time as shown in the graph below.
By analysing the evidence in the graph, find the amplitude of the oscillation of the pendulum and the time period of the pendulum.
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(b) A student carried out an investigation to find out how the time period of the pendulum depends on the length of the pendulum.
During the investigation she kept the mass of the pendulum bob and the angle of release constant. Her data is recorded in Table 1.
Table 1
Length of pendulumin Time for 10 swingsin Time
metres seconds periodin seconds
1 0.20 9.2 0.92
2 0.40 12.8 1.2
3 0.60 15.0 1.50
4 0.80 18.0 1.80
5 1.00 20.0 2.00
(i) Explain why the student timed ten swings, rather than just timing one swing, for each length of pendulum.
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(ii) In this question you will be assessed on using good English, organising information clearly and using specialist terms where appropriate.
Describe the steps that the student would take to obtain the data shown in Table 1.
In your description, comment on the number of decimal places and significant figures the student has used in each column.
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(iii) The student also carried out two more pendulum investigations.During the second investigation she kept the length of the pendulum and the angle of release constant. The data for this investigation is recorded in Table 2.
Table 2
Mass of pendulumbob in grams
Time for10 swings in seconds
Time periodin seconds
1 2.5 20.0 2.00
2 5.0 20.3 2.03
3 7.5 20.1 2.01
4 10.0 20.0 2.00
5 12.5 20.2 2.02
During the third investigation she kept the length of the pendulum and the mass of the pendulum bob constant. The data for this investigation is recorded in Table 3.
Table 3
Angle of releasein
degreesTime for 10 swingsin
secondsTime
periodin seconds
1 2 20.4 2.04
2 4 20.2 2.02
3 6 20.0 2.00
4 8 20.3 2.03
5 10 20.1 2.01
What conclusions can be made from the data recorded in Table 1, Table 2 andTable 3?Your answer should include a comment on the quality of the evidence.
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(c) The student replaced the pendulum bob with a light paper cone as shown in the diagram.
She plotted the displacement x of the pendulum bob against time as shown in the graph below.
The student concluded that the frequency of this pendulum decreased with time.Does the graph support her conclusion?
Explain the reason for your answer.
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(Total 15 marks)
Q19. Water waves can be made by vibrating a wooden bar up and down in a tray of water.
The bar moves up and down at a frequency of 5 hertz.
(a) Calculate the speed, in cm/s, of the water waves.
Write down the equation you use and then show clearly how you work out your answer.
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Wave speed = ................................... cm/s(3)
(b) The graph shows how the speed of deep ocean waves depends on the wavelength of the waves.
Use the graph to predict a speed for waves with a wavelength of 140 m.
Show clearly how you have used the graph to work out your answer.
Speed of waves = .................................. m/s(2)
(Total 5 marks)
Q20. The diagram shows a plane mirror used by a dentist to see the back of a patient’s tooth.
(a) Use a ruler to draw a ray of light on the diagram to show how the dentist is able to see the tooth labelled Z.
(3)
(b) Describe the image formed by a plane mirror.
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(Total 5 marks)
Q21. (a) Scientific research carried out in 13 countries has tried to find out if there are any links between using a mobile phone and developing different types of cancer.
About 13 000 people, half with cancer and half in good health, were interviewed about their mobile phone use.
(i) Suggest why people in good health were interviewed.
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(ii) Interviewing 13 000 people gave the researchers a large sample size.
Give one advantage, in any research project, of having a large sample size rather than a small sample size.
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(b) The following information was included in a newspaper article about the research project.
• It may be difficult to prove there is a link simply by asking people how much they use a mobile phone. People’s memories are not always accurate.
• Scientists in Israel found that people who use a mobile phone a lot are 50% more likely to develop a cancer on the salivary gland just in front of the ears.
• The cost of the research, £20 million, has been partly paid for by mobile phone companies.
• No children were included in the research.
(i) Draw a ring around the correct answer to complete the following sentence.
Using children in scientific research raises environmental issues.
ethical
social
(1)
(ii) Suggest two reasons why some people are concerned that the research was partly paid for by mobile phone companies.
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(iii) In Germany, mobile phones that emit very low levels of radiation are marked with a special symbol.
Explain why low emission mobile phones should be marked in this way.
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(Total 7 marks)
Q22. (a) The diagram shows a longitudinal wave being produced in a stretched spring.
(i) Use the bold words from the diagram to complete the following sentence. Put only one word in each space.
A longitudinal wave is one in which the ..................................... causing
the wave is parallel to the ..................................... of energy transfer.(2)
(ii) Name the type of energy that is transferred by longitudinal waves.
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(b) The diagram shows water waves made by a wave machine in a swimming pool.
Every second, two waves go past a person standing in the swimming pool.
The waves have a wavelength of 0.8 metres.
Calculate the speed of the water waves.
Write down the equation you use, and then show clearly how you work out your answer.
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Wave speed = ......................................... m/s(2)
(c) The graph shows how the speed of deep ocean waves depends on the wavelength of the waves.
What can you conclude from the graph?
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(Total 7 marks)
Q23. (a) The diagram shows a ray of light being reflected by a plane mirror.
Which of the angles, a, b, c or d, is:
the angle of incidence;
the angle of reflection? (2)
(b) The diagram shows a road junction seen from above.
A mirror placed at the side of the road allows the driver of car X to see car Y.
Using the same mirror symbol given in part (a), draw a plane mirror to show how it should be placed so that the driver of car X can see car Y.
(2)(Total 4 marks)
Q24. (a) Microwaves and visible light are two types of electromagnetic wave. Both can be used for communications.
(i) Give two properties that are common to both visible light and microwaves.
1 ............................................................................................................
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2 ............................................................................................................
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(ii) Name two more types of electromagnetic wave that can be used for communications.
................................................... and ..................................................(1)
(b) Wi-Fi is a system that joins computers to the internet without using wires. Microwaves, with a wavelength of 12.5 cm, are used to link a computer to a device called a router. Microwaves travel through the air at 300 000 000 m/s.
Use the equation in the box to calculate the frequency of the microwaves used to link the computer to the router.
wave speed = frequency × wavelength
Show clearly how you work out your answer and give the unit.
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Frequency = ..............................................................(3)
(c) Wi-Fi is used widely in schools. However, not everyone thinks that this is a good idea.
A politician commented on the increasing use of Wi-Fi. He said: ‘I believe that these systems may be harmful to children.’
However, one group of scientists said that there is no reason why Wi-Fi should not be used in schools. These scientists also suggested that there is a need for further research.
(i) Suggest what the politician could have done to persuade people that what he said was not just an opinion.
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(ii) Why did the group of scientists suggest that there is a need for further research?
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(Total 8 marks)
Q25. The diagram shows the seven types of wave that make up the electromagnetic spectrum.
Gammarays X-rays Ultravioletrays Visiblelight Infra redrays
Micro-waves
Radiowaves
(a) (i) Microwaves and visible light can be used for communications.
Name one more type of electromagnetic wave that can be used for communications.
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(ii) Name one type of electromagnetic wave that has a longer wavelength than microwaves.
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(b) Wi-Fi is a system that joins a laptop computer to the internet without using wires.A 2400 megahertz microwave signal is used to link a computer to a device called a router.
What quantity is measured in hertz?
Draw a ring around your answer.
frequency wavelength wave speed(1)
(c) A politician commented on the increasing use of Wi-Fi. He said: ‘I believe that these systems may be harmful to children.’
(i) Suggest one reason why more scientific research into the safety of Wi-Fi systems is needed.
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(ii) Complete the following sentence by drawing a ring around the correct line in the box.
a fact.
What the politician said was an opinion.
a prediction.
(1)(Total 5 marks)
Q26. (a) The table gives information about the frequencies in the hearing ranges of six different mammals.
Name of mammal Frequencies in hearing range
Bat 20 Hz → 160 kHz
Dog 20 Hz → 30 kHz
Dolphin 40 Hz → 110 kHz
Elephant 5 Hz → 10 kHz
Human 20 Hz → 20 kHz
Tiger 30 Hz → 50 kHz
(i) Which mammal in the table can hear the highest frequency?
...............................................................................................................(1)
(ii) Which mammal in the table, apart from humans, cannot hear ultrasound?
...............................................................................................................(1)
(iii) Give one example of a frequency which an elephant can hear but which a tigercannot hear.
Include the unit in your answer.
Frequency ............................................................(1)
(b) The diagrams show six sound waves, A, B, C, D, E and F, represented on an oscilloscope screen.
They are all drawn to the same scale.
(i) Which one of the waves has the greatest amplitude?
Wave ............................................................ .(1)
(ii) Which one of the waves has the highest frequency?
Wave ............................................................ .(1)
(Total 5 marks)
Q27. (a) Electromagnetic waves have many uses. The diagram shows two ways of sending information using electromagnetic waves.
(i) What type of wave is used to send information to and from satellites?
...............................................................................................................(1)
(ii) What property of this type of wave makes it suitable for satellite communications?
...............................................................................................................(1)
(b) The diagram shows two types of signal that can be used to send information. One of the signals is an analogue signal. The other is a digital signal.
Describe the differences between an analogue signal and a digital signal.
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................(2)
(c) Different frequency radio waves travel different distances through the atmosphere before being reflected.
Use the information in the diagram to describe the connection between the frequency of a radio wave and the distance the radio wave travels through the atmosphere before it is reflected.
........................................................................................................................
........................................................................................................................(1)
(d) Electromagnetic waves travel at a speed of 300 000 000 m/s.
A radio station transmits waves with a wavelength of 20 metres.
Use the equation in the box to calculate the frequency, in kilohertz (kHz), of these waves.
wave speed = frequency × wavelength
Show clearly how you work out your answer.
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
Frequency = .................................................. kHz(2)
(Total 7 marks)
Q28. Small sailing boats can be fitted with a passive radar device. The device increases the chance that the small boat will be seen on the radar screen of a large ship.The radar transmitter on the large ship emits microwaves.
(a) Microwaves and radio waves are both part of the electromagnetic spectrum.
How are microwaves different from radio waves?
........................................................................................................................
........................................................................................................................(1)
(b) How fast do microwaves travel through the air or a vacuum compared to radio waves?
........................................................................................................................(1)
(c) The diagrams show the position of a passive radar device on a small boat and the internal construction of one type of passive radar device.
Microwaves can be absorbed, reflected or transmitted by different materials and types of surface.
Explain what happens to the microwaves from the ship’s transmitter when they reach the passive radar device.
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................(2)
(d) Each type of passive radar device has an RCS value. The larger the RCS value, the easier it is for a small boat fitted with the device to be detected.
An independent group of scientists measured the RCS values of 4 different types of device. The RCS value for each device was measured in the same room using the same equipment.
(i) Why are the walls of the room covered in a material that absorbs the waves emitted by the radar transmitter?
...............................................................................................................
...............................................................................................................(1)
(ii) Why is it important to use the same room and the same equipment?
...............................................................................................................
...............................................................................................................(1)
(iii) Why is it important that the measurements are made by an independent group of scientists?
...............................................................................................................
...............................................................................................................(1)
(e) The movement of a small boat causes the mast and device to lean over, therefore the RCS values were measured at different angles.
The table gives the RCS values obtained by the scientists.
DeviceAngle X
0 ° 5 ° 10 ° 15 °
A 1.4 1.6 1.7 1.8
B 4.7 2.6 2.3 1.9
C 9.3 3.3 1.9 1.1
D 4.5 4.8 5.0 4.6
(i) Describe how the RCS values for device A are different to the RCS values fordevice B.
...............................................................................................................
...............................................................................................................
...............................................................................................................
...............................................................................................................(2)
(ii) The scientists recommended that a passive radar device fitted to a small boat should have:
• the largest possible RCS value
• an RCS value consistently above 2.0
Which one of the devices, A, B, C or D, would you recommend that someone fits to their boat?
.............................................
Give a reason for your answer.
...............................................................................................................
...............................................................................................................(1)
(Total 10 marks)
Q29. The diagram shows a model used to demonstrate an illusion known as ‘Pepper’s Ghost’.
A small light bulb and thin sheet of glass are put inside a box. The thin sheet of glass acts as a mirror. Although the light bulb is switched on, a student looking into the box cannot see the bulb. What the student does see is a virtual image of the bulb.
(a) Use a ruler to complete a ray diagram to show how the image of the light bulb is formed. Mark and label the position of the image.
(4)
(b) The image seen by the student is virtual.
Why?
........................................................................................................................
........................................................................................................................(1)
(Total 5 marks)
Q30. Radio waves and microwaves are two types of electromagnetic wave.
Both waves:
• can be used for communications
• travel at the same speed through air.
(a) Give two more properties that are the same for both radio waves and microwaves.
1 .....................................................................................................................
........................................................................................................................
2 .....................................................................................................................
........................................................................................................................(2)
(b) Some satellites are used to transmit television programmes. Signals are sent to, and transmitted from, the satellites using microwaves.
What is the property of microwaves that allows them to be used for satellite communications?
........................................................................................................................
........................................................................................................................(1)
(c) Terrestrial television does not use satellites.
Terrestrial television signals and radio signals both use radio waves.Radio signals are transmitted at a longer wavelength than terrestrial television signals.
My Revision Notes AQA GCSE Physics for A* – C, Steve Witney, © Philip Allan UK
In hilly areas it may be possible to receive radio signals but not receive terrestrial television signals.
Explain why.
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................(3)
(d) Electromagnetic waves travel at a speed of 3.0 × 108 m/s.
A radio station transmits waves with a wavelength of 2.5 × 102 m.
Calculate the frequency of the radio waves.
Use the correct equation from the Physics Equations Sheet.
Show clearly how you work out your answer and give the unit.
........................................................................................................................
........................................................................................................................
........................................................................................................................
Frequency = ......................................................................(3)
(Total 9 marks)
Q31. Diagram 1 shows a longitudinal wave being produced in a stretched spring.
(a) A longitudinal wave has areas of compression and areas of rarefaction.
Mark with the letter C, one area of compression shown in Diagram 1.(1)
(b) Diagram 2 shows the apparatus a teacher uses to demonstrate that sound can be reflected.
(i) Using a ruler, draw on Diagram 2 to show how sound from the loudspeaker is reflected by the sheet of metal to the sound sensor.
(2)
(ii) The teacher replaced the sheet of metal with a sheet of glass.
When he did this, the reading on the sound level meter went down.
Suggest why.
...............................................................................................................
...............................................................................................................(1)
(iii) The teacher changed the output from the loudspeaker to increase the amplitude of the sound wave produced.
What effect, if any, does this increase of amplitude have on the loudness of the
sound?
Draw a ring around the correct answer.
makes the sound quieter
does not change the loudness of the sound
makes the sound louder
(1)
(iv) The loudspeaker produces a sound wave at a frequency of 850 Hz. The wavelength of the sound wave is 0.4 m.
Calculate the speed of the sound wave.
Use the correct equation from the Physics Equations Sheet.
Show clearly how you work out your answer.
...............................................................................................................
...............................................................................................................
...............................................................................................................
Speed = ...................................................................... m/s(2)
(c) Music concerts are sometimes performed in sports halls. The concerts can be spoilt because of the sound reflected from the floor and walls.
What word is used to describe a reflected sound?
........................................................................................................................(1)
(d) The graph shows how the percentage of sound reflected from the floor and from the walls of a large room can be reduced by carpets and by curtains.
(i) Over which range of frequencies do curtains reduce the percentage of sound reflected the most?
Tick ( ) two boxes.
from 250 Hz to 750 Hz
from 750 Hz to 1250 Hz
from 1250 Hz to 1750 Hz
(1)
(ii) The manager of a sports hall plans to use the hall for regular music concerts. He has enough money to buy either carpet or curtains, but not both.
To improve the sound an audience hears, it would be better to hang curtains on the walls rather than laying a carpet over the floor.
Use the data in the graph to explain why.
...............................................................................................................
...............................................................................................................
...............................................................................................................
...............................................................................................................(2)
(Total 11 marks)
Q32. (a) The diagram shows the electromagnetic spectrum.
The pictures show four devices. Each device uses a different type of electromagnetic wave.
Draw one line from each device to the type of electromagnetic wave the device uses. One line has been drawn for you.
(3)
(b) Visible light waves travel through space at a speed of 300 000 km/s.
How fast do infrared waves travel through space?
........................................................................................................................(1)
(c) Draw a ring around the correct answer in the box to complete the sentence.
a longer wavelength than
Infrared waves have the same wavelength as visible light waves.
a shorter wavelength than
(1)
(d) The two diagrams, A and B, show a light ray travelling into a glass block.
(i) Look at Diagram A.
What name is given to the process that happens as the light enters the glass block?
........................................................................................................................(1)
(ii) Look at Diagram B.
The light enters the glass block without changing direction.
Why?
........................................................................................................................
........................................................................................................................(1)
(Total 7 marks)
Q33.The diagram shows a periscope being used to see over the heads of a crowd of people.
The periscope has been made using two plane mirrors.
(a) Using a ruler, complete the diagram to show how the second ray of light from a distant object reaches the person’s eye.
(2)
(b) How big is the image produced by the periscope compared to the size of the object?
........................................................................................................................(1)
(Total 3 marks)
Q34.The ship in the diagram is fitted with a navigation system. The navigation system works out the location of the ship by timing the microwave signals transmitted from at least three satellites.
(a) Microwaves are one type of electromagnetic wave.
Give two properties that all electromagnetic waves have.
1 ......................................................................................................................
........................................................................................................................
2 ......................................................................................................................
........................................................................................................................(2)
(b) The microwaves used in the navigation system are transmitted at a frequency of 1575 MHz.
Use the equation and information in the box to calculate the wavelength of the microwaves used in the navigation system.
wave speed = frequency × wavelength
microwaves travel at 300 000 000 m/s1 MHz = 1 000 000 Hz
Show clearly how you work out your answer.
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
Wavelength = ........................................ m
(3)
(c) The ship is fitted with a metal aerial that receives the microwave signals from the satellites.
For the navigation system to work, what effect must the microwave signals have on the aerial?
........................................................................................................................
........................................................................................................................(1)
(Total 6 marks)
Q35.The ship in the diagram is fitted with a navigation system. The navigation system works out the location of the ship by timing the microwave signals transmitted from at least three satellites.
(a) Microwaves are one type of electromagnetic wave.
Give two properties that all electromagnetic waves have.
1 ......................................................................................................................
........................................................................................................................
2 ......................................................................................................................
........................................................................................................................(2)
(b) The microwaves used in the navigation system are transmitted at a frequency of 1575 MHz.
Use the equation and information in the box to calculate the wavelength of the microwaves used in the navigation system.
wave speed = frequency × wavelength
microwaves travel at 300 000 000 m/s1 MHz = 1 000 000 Hz
Show clearly how you work out your answer.
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
Wavelength = ........................................ m(3)
(c) The ship is fitted with a metal aerial that receives the microwave signals from the satellites.
For the navigation system to work, what effect must the microwave signals have on the aerial?
........................................................................................................................
........................................................................................................................(1)
(Total 6 marks)
M1. (a) (i) 400 000 000orcorrect equivalent
allow 1 mark for correct transformation and substitution (of 75)answer 4 000 000 gains 1 mark only
2
(b) (i) any mention of alpha, beta, gamma waves scores 0 marks
emit / uses / transmit / receive microwavesaccept radiation for microwaves throughoutignore radio waves
1
some microwave / energy absorbed by / enters the bodyecf for their given electromagnetic wavedo not accept goes through the body
1
raises temperature of (body) cells / tissue / wateraccept reference to water molecules vibrating fasteraccept it could cause mutation / harm / kill cellsdo not accept answers in terms of ionisationignore references to cancer
1
(ii) any two from:
• research (may be) biasedor may have been misled in the pastaccept not independentor may be lying
• some research suggests a link
• long-term effect not proven / studiedaccept not studied for long enough
• residents may not have seen the research2
[7]
M2. (a) (i) 400 000 000orcorrect equivalent
allow 1 mark for correct transformation and substitution (of 75)answer 4 000 000 gains 1 mark only
2
(b) (i) any mention of alpha, beta, gamma waves scores 0 marks
emit / uses / transmit / receive microwavesaccept radiation for microwaves throughoutignore radio waves
1
some microwave / energy absorbed by / enters the bodyecf for their given electromagnetic wavedo not accept goes through the body
1
raises temperature of (body) cells / tissue / wateraccept reference to water molecules vibrating fasteraccept it could cause mutation / harm / kill cellsdo not accept answers in terms of ionisationignore references to cancer
1
(ii) any two from:
• research (may be) biasedor may have been misled in the pastaccept not independentor may be lying
• some research suggests a link
• long-term effect not proven / studiedaccept not studied for long enough
• residents may not have seen the research2
[7]
M3. (a) wavelength increasesaccept the crests are further apartignore waves are further apart
1
frequency decreasesaccept pitch decreasesignore references to amplitude
1
(b) stars / galaxies / sources emit all / different types of electromagnetic waves /radiationaccept two or more named electromagnetic wavesaccept answers in terms of frequencies / wavelengths
1
(c) (i) wavelength (of light) increasesaccept frequency decreases
orlight moves to red end of spectrum
accept redder but do not accept red alone1
(ii) it is the star (detected) furthest from theEarth
accept galaxy for starsorit is moving away the fastest
ignore reference to universe expanding1
(d) (i) all matter compressed to / starts at / comes from a single pointdo not accept increasing gravitational pullaccept everything / the universe for all matter
1
(massive) explosion sends matter outwardsaccept explosion causes universe to expandignore explosion creates the universe or further reference to star / Earth formation
1
(ii) check validity / reliability of the evidenceor
change the theory to match the new evidenceaccept comparison of new and old evidence
1[8]
M4. (i) all electromagnetic waves travel at the same speed through a vacuum , (soassume same speed in air)
accept ‘all parts of spectrum’ for electromagnetic waves1
(ii) 1500 (m)allow 1 mark for correct transformation and substitutionallow 1 mark for using 200 000 Hzanswers 1 500 000 = 1 mark
2
(iii) line drawn at correct positionanywhere between 1000 and next section (10 000)accept their value for (a)(ii) drawn inthe correct position
1[4]
M5. (a) (i) microwave1
(b) (i) identical1
(ii) • increased risk of cancerous growth (between ear and brain)1
• complaints of headaches and tiredness1
(iii) any two from:
• tests in a laboratory did not give effects of tiredness or headaches
• waves not strong enough to cause long term heat damage to cells
• evidence to link mobile phones and ill health is not reliable2
[6]
M7. (a) (mechanical) vibration(s)not just ‘particles knocking into each other’not reference to ‘sound particles’
1
(b) K1
(c) (i) reflected by the material from loudspeaker to microphone X1
shown by straight lines with angle of incidence = angle of reflection(by eye) and at least one arrow in the correct direction
do not credit if the direction is contradicted by any incorrect arrow / may be shown by waves / wavefronts in the direction of straight linesignore any sound to Y or which ‘misses’ the materialexample
1
(ii) any one from:
• so (the student) can compare results
• so only one (independent) variable
• to get reliable / accurate results
• because (the expanded) polystyrene absorbs some of the sounddo not credit just ‘so it’s a fair test’
1
(iii) [A] wood1
[B] either 0.25 or 1/4 or 25 % or 15/60 or 1: 3do not credit 1 : 4
1
(d) practical suggestion1
appropriate reason / explanationexample line / panel the walls with wood / plasterboard / increase the thickness of the plaster (on the walls) (1)(this) will absorb / reflect (back) (most / some of) the sound (1)credit legal suggestions for attempting to limit the noise made by the neighboursexample ask the neighbours to make less noise (1)by limiting the time(s) music played (1)do not credit reference to ‘sound particles’ for second mark
1[9]
M8. (a) C or 0.18 mm1
(b) 0.6 mallow 1 mark for correct transformation and substitutionallow 1 mark for changing frequency to Hzanswer 600 gains 1 mark
2
(c) creates an alternating currentaccept ‘ac’ for alternating currentaccept alternating voltage
1
with the same frequency as the radio waveaccept signal for radio wave
or it gets hotter1
(d) X-rays cannot penetrate the atmosphereaccept atmosphere stops X-raysdo not accept atmosphere in the way
or X-rays are absorbed (by the atmosphere)before reaching Earthignore explanations
1[6]
M9. (a) the normal1
(b) v1
(c) any one from:
• light has moved from glass to air / from air to glassaccept light has changed medium
• speed of light has changedbeware of contradictions for this marking point eg light has moved from glass to air and slowed down gets zero
• angle of incidence is less than the critical angleor (angle) i < (angle) c or (angle) y is less than the critical angle
• change in density (of medium)eg glass is more (optically) dense than air
1
(d) (i) ratio of v to y does not give the same answer (in every case)
or value of v doubles value of y does not double1
or increments for v are the same but increments for y are not the sameallow for 1 mark a calculation but no conclusioneg 30 → 60 19 → 35 (38)
1
(ii) as (angle) v increases, angle y increasesaccept as the angle of incidence increases, the angle of refraction increasesor there is a (strong) positive(non-linear) relationship between the variablesor ratio of sines is constantdo not accept angle y is not directly proportional to angle v
1
(iii) no evidence outside this rangeOWTTE
or when angle y is greater than the critical angle total internalreflection occurs
1[7]
M10. (a) (i) planeaccept any unambiguous indication
1
(ii) inverted1
virtualaccept any unambiguous indication
1
(b) reflection takes place at the surface of the pond and angle of incidence= angle of reflection
as judged by eye1
reflected ray is a straight line to frog’s eye through the air1
correct direction arrow either from insect or to frog’s eye
only one arrow essential butdo not accept if either arrow contradicted example of a fully correct response
1[6]
M11. (a) (i)correct order essential
(A =) a microphone1
(B =) an oscilloscopeor cathode ray oscilloscope or CRO
1
(ii) the amplitudeaccept any unambiguous indication
1
(iii) quieter / softerdo not accept less (which could refer to the amplitude, frequency or wavelength)
1
(b) sound cannot travel through a vacuum / (empty) space / free spaceaccept there is no medium for the sound to travel through
1
(because) there is / are nothing / no particles to vibrateaccept (because) there is / are nothing / no particles between them and the source (of the sound)
1
[6]
M12. (a) (i) compare (the health of) mobile phone users with non-mobilephone users
must be an implied comparison between users and non-usersany idea of doing an experiment negates the mark
1
(ii) increase the sample sizeaccept use more peopleaccept have a large sample sizerepeat the research / test is neutral
1
(iii) ethical1
(b) (i) so the phones can be compared (fairly)a fair test is insufficientaccept different tests (may) give different resultsdo not accept to make the results reliable, unless qualifiedeg all variables are controlleddo not accept bias unless qualified
1
(ii) yes all are below the legal limit / 2 (W/kg)
or no and any one from:
• even absorbing a small amount of energy may be harmfulaccept microwaves for energyaccept emits energy absorbed by head / other parts of body
• no proof that small amounts of energy are not harmfulaccept because the SAR value is not 0 (W/kg)
1
(c) any one from:
• to get an independent opinion
• company scientists may be biasedaccept company scientists may manipulate results
1[6]
M13. (a) reflection at the mirror of ray from tip of real puppy’s ear to real puppy’s eye (1)may be drawn freehand
accurate (1)ruler must have been used and the reflected ray is an extension of the straight line from point virtual ear however the virtual part of the line need not be shown
arrow to show correct direction (1)only one arrow needs to be shown but there must be no contradictionexample of (3) mark response
3
(b) flataccept ‘it’s not curved/bent’accept ‘it’s straight’
1[4]
M14. (a) C (only)1
(b) A (only)1
[2]
M15. (a) (i) radio(waves)1
(ii) energycorrect answer only
1
(b) (i) 0.0125 (m)allow 1 mark for correct transformation and substitution
2
(ii) make it hot(ter)do not accept cook itaccept (air) particles inside ball will move fasteraccept water in the ball gets hotter
1
(iii) wavelength decreasesignore reference to speed
1
frequency increases1
[7]
M16. (a) (i) shorter than1
(ii) increase slightly1
(b) (i) go up in the same ratioor (directly) proportional or as speed (of the tennis ball) increases so does the(difference in) frequency
accept as one goes up, so does the otheraccept positive correlation
1
(ii) 20 (m/s)allow 1 mark for showing correct method on graph(ie horizontal or vertical line anywhere on graph)if indicated by a cross, must be ± half square of correct value)
2
(iii) frequency and speed are both continuous variables1
[6]
##
(i) X-rays
infra red (rays)
radio (waves)all three in correct orderallow 1 mark for 1 correct
2
(ii) to kill cancer cells1
(iii) energy1
[4]
M18.(a) amplitude = 8 (cm)1
period = 4(s)1
(b) (i) same reading error for 10 swings as 1 swing1
so reduces (%) error in timingsorreduces error in an individual time periodaccept it makes timing errors less significantaccept increases reliability / precisionignore increases accuracy
1
(ii) Marks awarded for this answer will be determined by the quality of communication as well as the standard of the scientific response.
0 marksNo relevant content
Level 1 (1–2 marks)There is a basic description of the experimental steps but no correct reference to dps or sfs.
Level 2 (3–4 marks)There is a clear description of the experimental steps and correct reference to either dps or sfs
Level 3 (5–6 marks)There is a clear and detailed description of the experimental steps and correct reference to both dps and sfs
examples of the physics points made in the response
• measure the length of the pendulum with a ruler
• pull the bob to one side, measure the angle of release and release the pendulum bob
• time 10 swings / oscillations
• change the length of the pendulum and repeat
• divide each recorded time by 10
• number of decimal places for raw data depends on resolution of measuring device
• number of sf for Time period (1.80) depends on number of sfs for time for 10 swings (18.0)
6
(iii) as the length of the pendulum increases the time period increases, and this relationship is non-linear
do not accept they are directly proportional1
the time period does not depend on the mass of the pendulum bob or the angle of release
1
or
there is no relationship between either the mass of the pendulum bob or the angle of release and the time period
a specific statement illustrating that the conclusions are only valid within the limits of experimental uncertainty
eg there are always random uncertainties within any experiment. For Table 2 data repeating the experiment 5 times for the same mass of pendulum bob, you would expect a small variation in times between 20.0 s and 20.3 s.
1
or
a statement that the conculsions are only valid within the ranges measured for each variable
(c) No
time period does not change / always 4 seconds because1
frequency is constant / frequency is related to period (T =1 /f) and hence if period is constant frequency will be constant
1[15]
M19. (a) 40 (cm/s)correct answeran answer 0.4 m/s gains full creditif answer is incorrectallow 1 mark for correct wavelength λ = 8 cmorallow 2 marks for correct substitution into the correct equation, ie. V = 5 × 8orallow 2 marks for clearly stated wrong wavelength correctly substituted into correct equation and correctly calculated, ieλ = 16 cm/sV = 5 × 16 = 80
3
(b) line extended following pattern1
14 m/saccept their numerical value, if not 14,provided the first mark has been awarded
1[5]
M20. (a) ray drawn from tooth to mirror to eye1
angle I = angle Rjudged by eye
1
at least one arrow in correct directiondo not credit conflicting arrows
1
if no ruler used maximum mark is 2
(b) virtual1
upright1
[5]
M21. (a) (i) to compare mobile phone usage between the two groups1
(ii) enough data to indicate relationshipsorreduce effect of anomalous data1
(b) (i) ethical1
(ii) research may be biased (in favour of companies)1
negative effects on health may not get publishedaccept negative effects on health may be played down
1
(iii) it allows people to easily identify lower risk phones1
and this allows people to make a more informed choiceaccept and this allows a comparison to be made
1[7]
M22. (a) (i) oscillation1
direction1
correct order only
(ii) sound1
(b) 1.6allow 1 mark for correctsubstitution into correct equation ie 2 x 0.8
2
(c) as the wavelength increases so does the wave speed1
extra information eg wave speed increases faster between0-40 m than between 100-140 m
or
not in proportion1
[7]
M23. (a) b1
c1
correct order only
(b) mirror opposite road junction1
mirror facing correct way, angle correctjudged by eye
1[4]
M24. (a) (i) any two from:
• travel at the same speed (through a vacuum)accept travel at the speed of lightaccept air for vacuum
• can travel through a vacuum / spacedo not accept air for vacuum
• transfer energy
• can be reflected
• can be refracted
• can be diffracted
• can be absorbed
• can be transmitted
• transverseaccept any other property common to electromagnetic wavesaccept travel at the same speed through a vacuum for both marks
do not accept both radiated from the Sun2
(ii) infra redboth required for the mark
radio(waves)accept IR for infra red
1
(b) 2 400 000 000correct transformation and substitution gains 1 mark
ie or an answer of 24 000 000 gains 1 markeither 2 400 000 kHzor 2 400 MHz scores 3 marks but the symbol only scores the 3rdmark if it is correct in every detail
2
hertzaccept Hzdo not accept hz
1
(c) (i) presented (scientific) evidence / datado an experiment / investigation is insufficient
1
(ii) to find out if there is a hazard (or not)accept to find out if it is safeaccept not enough evidence to make a decisionnot enough evidence is insufficient
1[8]
M25. (a) (i) infra red (rays)accept IR
orradio (waves)
do not accept heat wavesdo not accept TV waves
1
(ii) radio (waves)this answer only
1
(b) frequency1
(c) (i)answer should be in terms of establishing if harmful or not harmful ie trying to clear up any uncertainty
do not accept answers that assume it is harmfuleg Wi-Fi systems will make you ill
need to know if it is harmful / makes you illaccept idea that safety issue may worry peopleaccept idea that (more) research may reassure peopleaccept idea of finding out (the truth)
1
(ii) an opinion1
[5]
M26. (a) (i) bat(s)1
(ii) elephant(s)1
(iii) any example in the inclusive range 5 ↔ 29 Hz / hertzappropriate number and unit both required
1
(b) (i) B1
(ii) F1
[5]
M27. (a) (i) microwaves1
(ii) can pass through the ionosphereaccept travels in a straight lineaccept atmosphere for ionospheredo not accept air for ionosphere
1
(b) any two from:
• analogue is continuously varyingdo not accept analogue has many values
• digital has only discrete valuesaccept digital is on or offaccept digital is 1 or 0accept digital is binary
• digital is less prone to interference (than analogue)accept digital is easier to restore
• digital can be processed more easily (than analogue) by a computer2
(c) higher the frequency, further the wave travels (into the atmosphere before reflection)
1
(d) 15 000allow 1 mark for correct transformation and substitution
ie an answer of 15 000 000 only gains 1 markallow both marks for an answer of 15 MHz (unit must be changed)an answer of 15 gains no credit
2[7]
M28. (a) higher frequencygeneral properties / uses are neutral
orshorter wavelength
do not accept different frequency / wavelength / energyorgreater energy
1
(b) the same (speed)accept they travel at the speed of light
1
(c) pass through / transmitted by the plastic / casing1
reflected by the metal / platesdo not accept bounce / deflected etc for reflected
if neither marking point scores an answer reflected (back to boat / from the device) scores 1 mark
1
(d) (i) waves are not reflected from the wallsaccept microwaves / radar for wavesdo not accept bounce / deflected etc for reflected
oronly waves (reflected) from the device are detected
accept to stop reflected waves affecting results1
(ii) different types (of device) can be comparedfair test is insufficientaccept idea that only one variable is then changed
1
(iii) so (measurements / results / scientists) are not biased towards one type / manufacturer of device/s
accept to avoid biasaccept so they are not biased
1
(e) (i) any two from:if temperature is mentioned rather than angle a maximum of 1mark can be scored
• (for any angle) A values < B valuesor converse eg B values are higher / better / stronger
• A values increase with (increasing) angleaccept weakest at 0° strongest at 15°values go up is insufficient
• B values decrease with (increasing) angleaccept strongest at 0° weakest at 15°values go down is insufficient
• A values do not vary as much (as B values)2
(ii) Dmark is for the reasonreason cannot score if D is not chosen
values are always over 2(.0)1
[10]
M29. (a) two rays drawn from the bulb and reflected by the glassangle I = angle R judged by eyeallow 1 mark for one incident and reflected ray even if angle Idoesn’t equal angle R
2
at least one arrow drawn in correct directionany conflicting arrows negate this markignore any arrows drawn on construction lines behind the glass
1
position of image correct
judged by eye1
(b) image is formed by virtual / imaginary rays crossingaccept construction lines only show where the light seems to come from
accept the image is behind the glass / mirroraccept image is seen through the glass / mirroraccept (real) rays of light do not pass through the imageaccept (real) rays do not crossaccept the image is a reflection (of the object)accept the image is formed by reflectiondo not accept a virtual image can’t be formed on a screendo not accept the object / image is reflected
1[5]
M30. (a) any two from:
• travel (at same speed) through a vacuum / spacedo not accept air for vacuum
• transverse
• transfer energy
• can be reflected
• can be refracted
• can be diffracted
• can be absorbed
• travel in straight lines2
(b) can pass through the ionosphereaccept atmosphere for ionospheredo not accept air for ionosphereaccept travel in straight linesaccept not refracted / reflected / absorbed by the ionosphere
1
(c) diffraction (of waves around hills)1
wavelength needs to be similar size to the obstacle / gap1
radio has a long enough wavelength or TV doesn’t have a long enough wavelengthan answer TV (waves / signals) have short wavelengths so do not diffract (around the hill) scores 2 marks
1
(d) v = f × λ
1.2 × 106 / 1200 000allow 1 mark for correct substitutionie 3.0 × 108 = f × 2.5 × 102
2
hertz / Hzdo not accept hz or HZaccept kHz or MHzanswers 1.2 MHz or 1200 kHz gain all 3 marksfor full credit the unit and numerical value must be consistent
1[9]
M31. (a) letter C clearly marking a compressionaccept C at any point in a compressionif more than one letter C marked all must be correct
1
(b) (i) straight continuous line drawn from loudspeaker to metal to sound sensorjudge by eye
1
angle I = angle Rjudge by eyeignore any arrows on lines
1
(ii) less sound reflectedaccept energy for sound
or
(some) sound passes through the glassaccept (some) sound absorbed by the glass
1
(iii) makes the sound louder1
(iv) v = f × λ
340allow 1 mark for correct substitutionie 850 × 0.4provided no subsequent step shown
2
(c) echo1
(d) (i) from 250 Hz to 750 Hz1
(ii) curtains reduce (percentage of) sound reflected more (than carpet)accept curtains absorb more sound (than carpet)
1
for all frequencies (shown)accept for both marks an answer in terms of walls having a larger (surface) area to reflect sound and curtains reducing the amount of reflected sound more (than carpet)answers less noisy or walls / curtains have a larger area gain 1mark onlydo not accept curtains are cheaper
1[11]
M32. (a) 3 lines drawn linking:
camera to visible light1
television to radio waves1
remote control to infrared
if more than one line is drawn from any device all those lines are incorrect
1
(b) 300 000 km/sunit required
or
300 000 000 m/s
accept the same (as light)accept the speed of light
1
(c) a longer wavelength than1
(d) (i) refractiondo not allow a misspelling that might be reflection
1
(ii) travelling along the normalaccept light is at 90° to the surface / blocklight is not entering at an angle is insufficient
1[7]
M33. (a) reflection shown at both mirrors1
ray parallel to given rayjudge by eye
1
(b) same size1
[3]
M34. (a) any two from:
• travel at the same speed (through a vacuum)if a value is given it must be correctaccept air for vacuumaccept travel at the speed of light
• can travel through a vacuum / spacedo not accept air for vacuum
• transfer energy
• can be reflected
• can be refracted
• can be diffracted
• can be absorbed
• transverse
• travel in straight linesaccept any other property common to electromagnetic wavesaccept travel at the same speed through a vacuum for both marksboth radiated from the Sun is insufficient
2
(b) 0.19 (0)accept any answer that rounds to 0.19accept 0.2 for all 3 marks provided working is shown0.2 without working gains 2 marksallow 2 marks for a correct substitution and transformation using frequency in hertz
ie wavelength = orallow 1 mark for changing MHz to Hzallow 1 mark for correct substitution using 1575 or incorrectly converted frequencyanswers 190476 and 190000 gain 2 marks
3
(c) create an alternating current with the same frequency(as the microwaves / signals / 1575 (MHz))
ignore reference to change in temperature1
[6]
M35. (a) any two from:
• travel at the same speed (through a vacuum)if a value is given it must be correctaccept air for vacuumaccept travel at the speed of light
• can travel through a vacuum / spacedo not accept air for vacuum
• transfer energy
• can be reflected
• can be refracted
• can be diffracted
• can be absorbed
• transverse
• travel in straight linesaccept any other property common to electromagnetic wavesaccept travel at the same speed through a vacuum for both marksboth radiated from the Sun is insufficient
2
(b) 0.19 (0)accept any answer that rounds to 0.19accept 0.2 for all 3 marks provided working is shown0.2 without working gains 2 marksallow 2 marks for a correct substitution and transformation using frequency in hertz
ie wavelength = orallow 1 mark for changing MHz to Hzallow 1 mark for correct substitution using 1575 or incorrectly converted frequencyanswers 190476 and 190000 gain 2 marks
3
(c) create an alternating current with the same frequency(as the microwaves / signals / 1575 (MHz))
ignore reference to change in temperature1
[6]
E1. In part (a)(i) a significant number of candidates divided by 75cm arriving at an answer of 4,000,000.
Part (b)(i) produced a wide range of answers; however few candidates scored all three marks. Many candidates scored two marks for the idea of ‘microwaves damaging cells’. Most candidates scored at least one mark in part (b)(ii) with almost half scoring full credit. The idea that research could be biased and the need to present the evidence was well known.
E2. In part (a)(i) a significant number of candidates divided by 75cm arriving at an answer of 4,000,000.
Part (b)(i) produced a wide range of answers; however few candidates scored all three marks. Many candidates scored two marks for the idea of ‘microwaves damaging cells’. Most candidates scored at least one mark in part (b)(ii) with almost half scoring full credit. The idea that research could be biased and the need to present the evidence was well known.
E3. Part (a) was generally well answered. The link between increasing wavelength and decreasing frequency was usually correctly identified. Some candidates referred to amplitude correctly, although irrelevant to the question.
Part (b) was poorly answered. Those candidates who had the right idea could often not express themselves clearly enough to gain credit. Many candidates were thinking about sending signals rather than receiving them.
Part (c) was poorly answered. In part (c)(i) many candidates failed to gain credit because they answered in terms of what the red shift tells us rather than what it is. Some candidates with the correct idea referred to the star or galaxy moving to the red end of the spectrum, rather than the radiation. In part (c)(ii) many candidates did not gain credit because they gave a generalised answer about red-shift rather than the red shift of the particular star in the question.
Although there were some good answers to part (d)(i) there were also many misconceptions, e.g. confusing the big bang with supernovas or with the creation of the Earth and the creation of life on Earth. Some candidates understand the big bang as an interim stage; ‘all the galaxies came together and exploded’. Whilst a number of candidates talked of matter being created by the explosion. In part (d)(ii) many candidates understood the need the check the reliability of the evidence.
E4. In part (i) few candidates realised that since both light and radio waves travel at the same speed in a vacuum they are likely to travel at the same speed through air. In part (ii) many candidates calculated the correct answer. The most common error was not to convert kHz to Hz. Part (iii) was not attempt by a significant number of candidates.
E5. In part (a)(i), the correct answer of microwaves was given by only about 50% of candidates.
In part (b)(i) most candidates were aware of the need for identical results to confirm the reliability of an investigation. Although parts (b)(ii) and (b)(iii) were both worth two marks the vast majority of candidates were satisfied, in each part, to supply only one piece of information from the newspaper article. For this reason most candidates scored only one mark for each part.
E6. Many candidates made a good start with this question. The most common error being in part (c) where candidates were unable to understand that radio waves could be reflected by the Earth’s atmosphere.
In part (d) it was disappointing to see that many candidates were unable to match the shortest wavelength with the waves next to the smallest number on the diagram.
E7. Foundation tier
(a) A majority of candidates knew that sound waves are caused by vibrations.
(b) The great majority of candidates correctly identified graph K.
(c) (i) Many candidates correctly showed reflection at the surface towards microphone X and, by eye, the angle of incidence appeared to equal the angle of reflection.
However some candidates did not gain a second possible mark as they failed to indicate the direction with an arrow.
(ii) About half the candidates were able to give an appropriate reason such as ‘to keep the other conditions the same’. However those who just offered ‘so it’s a fair test’ did not gain credit.
(iii) [A & B] Most candidates correctly identified ‘wood’. However only about a quarter of candidates were able to translate the data into a proportion and many just suggested 15 (arbitrary units).
(d) The great majority of candidates were able to gain a mark for a practical suggestion but many just went on to ‘repeat the question’ by way of explanation. For example, ‘…and this will reduce the transmitted noise’ rather than, for example, ‘…and more of the sound will be absorbed/reflected back’.
Higher tier
(a) Nearly all candidates knew that sound waves are caused by vibrations. However a small minority were incorrect to state that sounds are caused by molecules in the air colliding with each other, since countless billions of them are continually doing that in silent places.
(b) The great majority of candidates correctly identified graph K.
(c) (i) Nearly all candidates correctly showed reflection at the surface towards microphone X and, by eye, the angle of incidence appeared to equal the angle of reflection. However, some candidates did not a gain a second possible mark because they failed to indicate the direction with an arrow.
(ii) Most candidates were able to give an appropriate reason such as ‘to keep the other conditions the same’. However, those who just offered ‘so it’s a fair test’ did not gain the mark.
(iii) Nearly all candidates correctly identified ‘wood’ however, some were not able to translate the data into a proportion and many just suggested 15 (arbitrary units). The examiners credited one quarter, 0.25, 25%, and 1:3 but not 1:4 which was a fairly popular, but incorrect, response for those who attempted to express the proportion as a ratio.
(d) Almost all candidates were able to gain a mark for a practical suggestion, such as ‘fit wood panelling’ or ‘plaster the wall’ or ‘plaster to a greater thickness’, but some just went on to ‘repeat the question’ by way of explanation. For example, ‘…and this will reduce the transmitted noise’ rather than, for example, ‘…and more of the sound will be absorbed/reflected back’.
E8. (a) Although this was answered correctly by the majority of candidates, many did not use the given wavelength of visible light as a clue to obtaining the correct infra red wavelength.
(b) Most candidates correctly transformed and substituted into the equation, but many candidates did not score the second mark through not converting kHz to Hz.
(c) Very few candidates scored at all on this question; a small number gained one mark for the heating effect.
(d) Only a minority of candidates scored the mark for this question. Common misconceptions were that clouds or light pollution would affect the detection of Xrays, or that the X-rays were being sent from the telescope to the star, or that satellite telescopes were much nearer to the stars than terrestrial telescopes.
E9. (a) Nearly all candidates could name the normal.
(b) Nearly two-thirds of candidates recognised that, on the diagram, v is the angle of refraction.
(c) Just over two thirds of candidates knew why refraction has taken place.
(d) (i) Candidates generally secured two marks by comparing the values for 30° and 60° or for 40° and 80°. Credit was also given for other mathematically correct responses
such as, ‘the angles are not directly proportional because v ÷ y is different for every pair. For example, it’s 1.58 for the first pair and 1.95 for the final pair’.
(ii) Nearly two thirds of the candidates were able to offer a correct conclusion.
(iii) Just over half of the candidates were able to explain that the conclusion is only valid in the range 30° to 80° because there is no evidence outside this range.
E10. (a) (i)(ii) Most candidates knew that the surface of a pond acts like a plane mirror but only a small minority chose both of the words ‘inverted’ and ‘virtual’ to describe the image in the pond. Many candidates chose one of these words correctly.
(b) This was rarely answered correctly for three marks. Common errors were;
• to show reflection taking place other than at the surface of the water
• to show the direction of light from the frog to the insect.
E11. (a) (i)(ii) Most candidates correctly identified the equipment as a microphone and an &(iii) oscilloscope but most incorrectly stated that the distance x represents half the amplitude of the sound wave, and that when x becomes smaller the pitch/frequency/ wavelength of the sound becomes less.
(b) Most candidates gained some credit for knowing that sound cannot travel through a vacuum but many, by failing to make it clear that space contains nothing to vibrate, did not gain a second mark.
E12. Foundation Tier
(a) (i) Many candidates suggested carrying out a practical experiment such as putting a group of people in a room and forcing them to use a mobile phone constantly to see if they became ill. Answers along these lines were not creditworthy.
It was expected that candidates would suggest a survey, in which health comparisons were made between a group of phone users and a group that did not use a phone. This was what most of the better candidates suggested. Some candidates however, chose the wrong groups to compare and they suggested comparing phone users who were ill with phone users who were not ill.
It was disturbing to see how many candidates believed that the main problem with mobile phones is that they are radioactive.
(ii) The best way to improve the reliability of a survey is to increase the sample size, and most of the better candidates stated this. Simply ‘repeating’ is not good enough.
(iii) Half of the candidates chose the correct answer of ‘ethical’.
(b) (i) Many candidates were using the terms ‘reliable’, ‘accurate’, ‘precise’ and ‘valid’ (and sometimes all of these) without showing any understanding of their meaning, thus scoring no marks. As with ISAs, the term ‘fair test’ on its own, without any further explanation, does not qualify for a mark.
Only the better candidates realised that, unless the tests were the same, it is not possible to make any comparison between the phones.
(ii) The majority of candidates answered this question correctly, either by stating ‘Yes, because all the values are below 2.0’ or ‘No, because even low levels of radiation may be harmful’.
(c) The majority of candidates realised that scientists employed by the company that made the devices could be accused of being biased.
Higher Tier
(a) (i) Only half the candidates answered this correctly. The most common correct answer was some reference to noise/interference with some candidates giving very detailed explanations of the removal of interference from the signal. Only a small number of candidates referred to the use of digital signals in computers and although a number had the idea of digital being better they often went on to talk about an improved picture or sound rather than discussing the quality of the signal.
(ii) The majority of candidates gained the mark for referring (sometimes in great detail) to the use of microwaves in cooking.
A small number gave the simple response ‘in a microwave’ and did not earn any credit. Only a few candidates mentioned the use in communications but most of these answers incorrectly referred to radio/television or even the TV remote control.
(b) (i) Only a minority of candidates gained the mark here. Most of the candidates knew that they needed to study the health of users/non-users but unfortunately the vast majority intended to do some sort of experiment which involved making volunteers use phones over a period of time and monitoring them. Candidates should be aware that medical experiments are not done on people to see if something is harmful. Those candidates who were going to research users health quite often neglected to mention that they would need to compare with non-users. Some candidates who used the term test/experiment went on to explain that they would study health data demonstrating that the terminology in this question was a problem. The candidates’ confusion and poor expression of ideas in a limited space was a concern.
(ii) Whilst many answers may have indicated the idea of increasing the sample size, the wording tended to be too brief or imprecise, for instance ‘repeat the test’ without specifying whether this was with other people or the same set of people.
(iii) Virtually all candidates identified the issue as being an ethical one.
(c) (i) Many candidates were using the terms ‘reliable’, ‘accurate’, ‘precise’ and ‘valid’ (and sometimes all of these) without showing any understanding of their meaning, thus scoring no marks. As with ISAs, the term ‘fair test’ on its own, without any further explanation, does not qualify for a mark. A significant minority of candidates realised that, unless the tests were the same, it is not possible to make any comparison between the phones.
(ii) A fairly straightforward question that was well answered. Most of those who did not score gave answers that had nothing to do with the information given or referred to microwaves being emitted rather than absorbed. Some candidates answered in terms of mobile phone masts and thus could not be given credit as they did not answer the question that was asked.
(d) Almost all candidates scored a mark here for demonstrating the need to avoid bias or the possibility of result manipulation. The candidates have perhaps too readily accepted the idea that people cannot be trusted to do a job properly or examine data impartially if given enough financial incentive to do otherwise.
E13. (a) Less than a third of candidates gained full marks. Many either gained no marks or made no attempt at the question.
(b) Less than half the candidates could give a correct meaning to the term ‘plane’ in the context of a plane mirror. Some suggested it means a mirror without ornamentation.
E14. Most were able to identify the wave patterns with the smallest amplitude and with the lowest frequency.
E15. (a) (i) This was generally known. A common incorrect answer was ‘radio active waves’.
(ii) Less than half the candidates knew that energy is transferred by a wave.
(b) (i) There were a disappointing number of candidates who could not rearrange the equation. Many candidates tried multiplying the two numbers ending up with a value that they obviously did not consider unrealistic. Of those candidates who did rearrange the equation correctly, many were unable to deal with the large number of
zeros. A few candidates pointed out on their scripts that their calculators were unable to handle such large numbers. Candidates seem to have lost the ability to cancel out before using a calculator.
(ii) A significant number of candidates linked the idea of a substance that absorbs microwaves having a rise (albeit very small) in temperature.
(iii) Many candidates demonstrated a good understanding of this topic, realising that it was about the Doppler Effect, and gained both marks.
E16. (a) (i) The majority of candidates picked up the clue from the diagram, and correctly stated that the wavelength of the microwaves reflected from the ball are shorter than those from the speed gun.
(ii) The majority of candidates identified that the temperature of the ball will increase slightly.
(b) (i) Some candidates appeared not to understand what was meant by the word ‘pattern’. Thus they were offering answers such as ‘It goes straight up’. Most candidates did score a mark here, even if they stated that the frequency was increasing rather than the difference in frequency increasing.
(ii) It was pleasing to see that most candidates were able to obtain the correct answer of 20m/s. The most common mistake was to read the scale on the y axis incorrectly: many candidates thought that they needed to count two little squares up from the 3000Hz line to reach 3200Hz. They therefore reached a figure of more than 20m/s. Those candidates who heeded the advice in the rubric to ‘show clearly on the graph how you obtain your answer’ were able to score one mark if they showed a suitable method on the graph, even if they subsequently arrived at the wrong answer.
(iii) The majority of candidates selected the correct answer.
E17. (i) Most candidates knew that radio waves have the longest wavelength, but many put X-rays and infra red rays the wrong way round.
(ii) Most candidates realised that a use of gamma rays is to kill cancer cells.
(iii) Only about 50% of the candidates knew that electromagnetic waves move energy from one place to another.
E24. (a) (i) It appeared that the term .properties. was not understood by many candidates, and answers giving uses of the waves were more frequently seen. Candidates should be aware that they do not generally gain credit for repeating information which they have been given in the question, so saying that both waves were electromagnetic or that both could be used for communications did not score any credit.
(ii) This question was correctly answered by just under three quarters of candidates, although some candidates gave .visible light and microwaves. as an answer, failing to realise that the question had already referred to these waves.
(b) Although a large number of candidates were able to transform the equation and substitute values, the majority failed to convert the wavelength from centimetres. The majority of candidates either did not read that they also had to give the unit, or perhaps did not know what the unit was, but those who gave the unit usually did so correctly.
(c) (i) Many candidates seemed to have the correct idea but failed to express themselves correctly. A common incorrect answer was to suggest that the politician should carry out an experiment.
(ii) A surprisingly large number of answers indicated that candidates had read the question as asking why there was ‘no need for further research’. Other answers included terms such as ‘bias’, ‘valid’ and ‘accurate’ that did not answer the question.
E25. (a) (i) Most candidates correctly chose radio waves or infra red.
(ii) Only just over half of the candidates correctly stated that radiowaves have a longer wavelength than microwaves.
(b) Just under half of the candidates knew that it is frequency that is measured in hertz.
(c) (i) Only the better candidates realised that the purpose of doing more scientific research is to obtain evidence and establish whether or not Wi-Fi is harmful. Many candidates started from the assumption that Wi-Fi is harmful, and that the research was to find ways of reducing the harm. Some candidates misunderstood the question and talked about the dangers of allowing children to access the Internet.
(ii) Most candidates realised that the politician’s statement was an opinion, although a significant number of candidates assumed that it was a fact.
E26. (a) (i) (ii) (iii) Nearly all candidates gave the correct mammals although fewer candidates were able to give a correct example of a frequency partly because a number used an incorrect unit, many candidates using kHz.
(b) (i) (ii) Most candidates correctly identified the relevant diagrams but there is some confusion between how amplitude and frequency are shown diagrammatically and some candidates tended to answer from first impressions rather than looking carefully at the diagrams.
E27. (a) (i) Answers were divided between microwaves and radio waves, with fewer than half of the candidates choosing the correct answer.
(ii) Not many answers were linked to the satellite communication idea; instead general properties of microwaves or radio waves were given.
(b) This question was quite well answered, with the majority of candidates correctly describing a digital signal, although the continuous variation of an analogue signal was not always referred to.
(c) The majority of answers to this question were correct.
(d) Few candidates scored both marks. Many candidates were able to transform the equation correctly, and substitute values to give an answer of 15 000 000, however the majority of answers were left at this value and not converted into kHz.
E28. (a) This was a poorly answered question. Many candidates wrote about the uses of the two waves instead of the way in which the waves themselves were different or simply said that the wavelength / frequency was different without stating how.
(b) Again a poorly answered question, with many candidates believing that the waves would travel at different speeds. Just over one-fifth of candidates did not attempt this part question.
(c) Only a small percentage of candidates scored both marks for this question, as the majority of candidates failed to refer to what happened to the microwaves when they reached the plastic casing. Of those who did refer to this, many were confused between absorption and transmission.
Many candidates gained one mark for stating that the microwaves would be reflected, but some candidates lost this mark because they used the word ‘bounce’ or ‘deflect’ instead of ‘reflect’.
(d) (i) Very few correct answers were seen to this question. Most candidates thought that the waves had to be absorbed in order to stop them escaping from the room and then possibly harming people.
(ii) A very poorly answered question, with the majority of candidates simply stating that this was in order to make it a fair test.
(iii) Only the better candidates realised that this was in order to eliminate any possible bias, but many candidates simply repeated their ‘fair test’ answer.
(e) (i) Just over half of the candidates were able to score at least one mark here, although some of the weaker candidates thought that as the measurement was in degrees it must be referring to temperature.
(ii) This question was correctly answered by about half of the candidates.
E29. (a) Very few students were able to locate the correct position of the image. Many students were able to draw one ray from the object to the glass and show it reflecting towards the eye, but in most cases, the angle of incidence was significantly and obviously different to the angle of reflection. If arrows were drawn on the rays, they were mostly shown in the correct direction. A second ray from the object and construction rays behind the glass were rarely seen. Less than a tenth of students achieved three or four marks.
(b) Very few answers explained that the image is formed by virtual / imaginary rays crossing.
E30. (a) Considering the large number of wave properties to choose from, students did not score well on this question. Only a tenth of students could give two correct properties.
(b) Few correct responses referring to microwaves being able to pass through the ionosphere were seen.
(c) A large number of students did not recognise that the radio waves were being diffracted. Of those who did, the majority were able to relate the amount of diffraction to the wavelength of the waves, but very few students explained the relationship between gap width, wavelength and diffraction.
(d) Most students were able to identify the correct equation, and many were able to transpose and substitute correctly. Mathematical errors, often involving powers of ten, were then quite common. The unit of frequency was often omitted or written incorrectly as ‘hz’.
E31. (a) About three-quarters of students could correctly identify a region of compression in the spring.
(b) (i) There were many excellent responses to this question scoring both marks. However, a significant number of students failed to score both marks because of the careless way in which the lines had been drawn. Examples included angles being nowhere near equal, large gaps between the ray and the reflecting surface and lines starting and finishing large distances from the speaker and the sound sensor.
(ii) Over half of students were able to suggest a suitable reason for the reading on the sound level meter going down.
(iii) About two-thirds of students correctly chose 'makes the sound louder'.
(iv) The calculation of the speed of sound was generally well done with three-quarters of students scoring both marks.
(c) A surprisingly large number of students did not know that a reflected sound is called an echo. Almost a fifth of students did not attempt this question.
(d) (i) Half of the students correctly chose the frequency range from 250 Hz to 750 Hz.
(ii) Only the better students realised that the reason why curtains would be better than carpet is because curtains reflect less sound. Many thought that carpet would be a better choice, in spite of the fact that in the stem of the question they were told that curtains would be better. In some of these cases, it was clear that students thought that reflection of sound was a good thing. In some cases, students thought that because the line for carpet on the graph was higher than the line for curtains, it must therefore be better. Very few students could make a sensible reference to the frequencies shown on the x-axis. Some students thought that curtains and carpet were able to change the frequency in different ways.
E32. (a) Surprisingly, less than a third of students scored all three marks. Many linked ‘television’ to ‘visible light rays’. Perhaps they had misread the question as being ‘which type of wave the device produces’ rather than ‘which type of wave the device uses’.
(b) This was the Quality of Written Communication (QWC) question on the paper which required the students to demonstrate their ability to use good English, organise their information clearly and use specialist terms where appropriate. Many students were able to supply some basic information as physics points, but often their responses lacked either the structure and organisation or the logical sequencing to achieve Level 2 and score three or four marks.
(c) Only just over half of students knew that infrared waves have a longer wavelength than visible light waves.
(d) (i) Again poorly answered, only a third of students recognising the process as refraction. Most thought that the process was either reflection or diffraction.
(ii) Many students found it difficult to express themselves clearly enough to gain a mark here. It was common to read answers such as ‘the light is not entering at an angle’ or ‘the light is entering straight’. Some students were writing that there is no normal, while others went further and stated that there needs to be a normal for the light to bounce off.
E33. (a) Nearly 72% of candidates achieved full marks for completing the periscope diagram, although 9% of candidates were completely wrong. Pupils without rulers did find this item more challenging.
(b) Few candidates actually thought about the size of an image in a plane mirror and most answered the question in terms of their own rather inaccurate diagrams. Only 31% of candidates answered correctly.
E34. (a) Many students were able to give one correct property, but few were able to give two.
(b) A large number of students were able to transform the equation correctly, but common mistakes were either not converting MHz to Hz or converting it incorrectly.
(c) Although this answer merely required recall of a statement given in the specification, very few correct answers were seen.
E35. (a) Many students were able to give one correct property, but few were able to give two.
(b) A large number of students were able to transform the equation correctly, but common mistakes were either not converting MHz to Hz or converting it incorrectly.
(c) Although this answer merely required recall of a statement given in the specification, very few correct answers were seen.
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