Inquiry on waves knowledge handouts and notes

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Grade 8 Vocabulary List 1 1. wave

2. mechanical

3. electromagnetic

4. amplitude

5. wavelength

6. frequency

7. reflection

8. refraction

9. diffraction

10. pitch

11. resonance

12. overtone

13. eardrum

14. radiant

15. spectrum

16. infrared

17. radiation

18. gamma ray

19. medium

20. lens

21. retina

22. inquiry ** Need to write for each word: 1. Definition 2. Your own sentence

_____________________________________________ (Summary for Section 1 of Chapter 16) (Main Idea) Waves are a kind of _____________________________ and possess certain properties. There are also different kinds. (Supporting Idea 1) Waves are ____________________ that have rhythm. They carry ____________ but ________________________. (Details) Waves can occur in water from running boats. Also, the sound made from a streak of lighting is a wave. It is important to emphasize that waves cause energy to move –but- no matter moves. (Supporting Idea 2) Scientists believe many waves (but not all) work by molecules ____________________. This is a model only. (Details) One molecule has energy. It then passes some energy to the next molecule. That molecule passes it to another molecule and so on. It is similar to passing a ball. (Supporting Idea 3) Mechanical waves always transfer energy through molecules. So they need some ____________________ that has molecules in it to work. (Details) For example, water waves work through water molecules. Sound waves travel through almost any solid, liquid or gas such as air. (More Details) One kind of mechanical wave is a ____________________. Here, energy is passed by molecules moving ________________________ or at right angles to the direction the wave travels. There are peaks and valleys called crests and troughs. See figure 3 on page 464. The peaks are called crests and the valleys are called troughs. (More Details) Another kind of mechanical wave is a _______________________. Here, molecules move forward and backward along the direction the wave moves in. See figure 4 on page 464. The molecules move a little but they always return to the original positions. Only energy travels somewhere. A coiled spring is a good example. (Supporting Idea 4) _______________________ are a common example of compressional waves. They are produced by something that is vibrating. (Details) When some object vibrates, it may first move up. As a result, molecules are pushed closer together. This is called a compression. Then the object moves down. As a result, the molecules have more room and spread out and away. This is called a rarefaction. This action is repeated again and again as the object continues to vibrate going up and down. The series of compressions and rarefactions forms the sound wave. See figure 5.

(Supporting Idea 5) Electromagnetic Waves _________________________ so they can travel in space. (Details) Examples include radio waves, visible light waves and ultraviolet rays. The _______________ also produces many kinds of electromagnetic waves.

SUMMARY – Organizer Handout (for Chapter 16, Section 2, pg. 467) Step 1: Read one time. * Take notes too if you want!

Step 2: Write the Main Idea (1-2 sentences) –_________________________________________________ _______________________________________________________________________________ _______________________________________________________________________________ _______________________________________________________________________________

Step 3: Write the supporting ideas. Write in the small boxes first!

Step 4: Write the supporting details. Write in the bigger boxes later!

Supporting Idea 1 (1-2 sentences)

Supporting Details 1 (1+ sentences)

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Reading Notes



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1 Missing Handout after Computer Crash- - Summary note on Wave Behavior (Chapter 16, Section 3, page 472) * see me for these if you need them until I fix this problem. Sorry!

What are Electromagnetic Waves? An electromagnetic wave is a special kind of wave that is produced by charged particles in motion. It does not require a medium to travel in. How does an Electromagnetic Wave Work? An electromagnetic wave carries radiant energy. Almost anywhere in the universe, there exists various charged particles such as electrons or protons. (even in space!) Charged particles are special because they are surrounded by electric fields. An electric field is some kind of force field. electric field

Ex. a proton

As well for certain reasons, a charged particle may start moving. When a charged particle starts moving, a second kind of force field is formed: a magnetic field. (just like with a magnet) magnetic field

Ex. an electron Finally, when a charged particle is moving up and down, its electric field and its magnetic field move farther and farther away in many directions. They also move with a wave like motion. Eventually, the electric field may strike another charged particle and cause it to move. Then, this particle produces both an electric field and a magnetic field. In the process, the wave continues through the movement of its two force fields. As more and more charge particles are hit, their vibration extends the wave and energy thus moves. (see figure 5 on pg. 523)

SUMMARY – Organizer Handout (for Chapter 18, Section 2, pg. 525) Step 1: Read one time. * Take notes too if you want!

Step 2: Write the Main Idea (1-2 sentences) –_________________________________________________ _______________________________________________________________________________ _______________________________________________________________________________ _______________________________________________________________________________

Step 3: Write the supporting ideas. Write in the small boxes first!

Step 4: Write the supporting details. Write in the bigger boxes later!



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Reading Notes



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(knowledge) The Electromagnetic Spectrum (for Chapter 18, Section 2, pg. 525)

There is a huge range of electromagnetic waves in any given space. These waves differ according to their frequencies and wavelengths. Moreover, how short their frequencies and how long their wavelengths are gives rise to a different type of electromagnetic wave with its own distinct characteristics.

How Different Types of Electromagnetic Waves are Produced- Something (ex. an antenna from a radio or tv tower, a star in space, lightning in the sky) cause some charged particles to move. The energy given to these particles causes them to vibrate at different speeds. The different speeds of the particle vibration in create electromagnetic waves of different wavelengths and frequencies that have specific characteristics and uses. (see Figure 7 on pg. 525 of your textbook for summary diagram)

Types of Electromagnetic Waves-

1. Radio Waves– these are electromagnetic waves having very low frequencies and therefore very long wavelengths. Their wavelengths are longer that 0.3 m. These waves are used to transmit both radio signals (that give rise to sound through radio speakers) and tv signals (that give rise to pictures on tv screens). By changing the wavelength very slightly, you can transmit radio or tv signals at different frequencies of channels as has been done for radio and tv stations.

2. Microwaves- these electromagnetic waves are shorter than radio waves but still pretty long. Their wavelengths are between 0.3 m and 0.001 m. These waves are used by cell phones to transmit sound and even video. Microwave ovens also use them to make food molecules vibrate faster which warms the food in turn. Radars also work on microwaves. Some device produces them where they are reflected off of nearby objects and bounce back. The device then measures things like the time for reflection to determine how close the object and also its location. Bats and dolphins do the same thing

3. Infrared Waves- these electromagnetic waves have wavelengths between 0.001 and 0.000 007 m. Because the charged particles for these waves are moving much faster, heat is generated by these waves. Every object emits infrared waves because all atoms and molecules are in constant movement which causes their associated charged protons to move too and create waves. Special instruments called infrared detectors can distinguish objects based on differences in the infrared waves they produce from other things in their surroundings. Some night visions gadgets work in this way and certain animals such as pit vipers can detect infrared waves to hunt prey at night.

4. Visible Light- when charged particles are stimulated to generate waves of a higher frequency by a fast enough vibrating object, not only is more heat produced but light is produce as well. Visible light has a wavelength between 0.000 007 and 0.000 004 m. By slight changes in a wavelength within this range, different shades of colour are produced.

5. Ultraviolet Radiation- here waves are produced between 0.000 004 and 0.000 000 000 1 m. Because the waves are produced by faster vibrating objects, they carry more energy. Consequently, these waves can damage certain molecules including many molecules that make up living cells.

Moreover, too much ultraviolet radiation can kill healthy cells. Sun burn results in this way. Sun glasses protect you from ultraviolet radiation by reflecting the waves away from your eyes.

One of the best protectors from UV radiation is the earth’s ozone layer. It keeps out most of the UV radiation from the sun. However, it is being damaged by certain chemicals created by air pollution.

However, a little ultraviolet radiation is actually good for you because it stimulates the production of vitamin D by your body. Also, UV radiation is important for disinfecting things such as lab equipment. Sterilizers use UV rays.

6. X rays and Gamma Rays – these electromagnetic waves have extremely tiny wavelengths. As a result, they carry a lot more energy and can damage many things that they hit. For instance, they can go right through skin and muscle. Lead can be used a shield for X rays. Gamma rays are produced from nuclear fusion and fission and cause the greatest damage.

X rays are useful in creating images of the body for doctors because when they pass through the body, they are absorbed at different degrees due to varying densities of the body. An special image can be obtained to reflect what a part or region inside the body looks like.Gamma rays can be used to treat cancer by having them targeted on cancerous tumors. Harmful bacteria can be treated in a similar fashion.

Technology

Inquiry on waves knowledge handouts and notes