10 Mains Electricity
208minutes
208marks
Q1.The diagram shows an a.c. generator.
The coil rotates about the axis shown and cuts through the magnetic field produced by the magnets.
(a) (i)A potential difference is induced betweenXandY.
Use the correct answer from the box to complete the sentence.
electric
generator
motor
transformer
This effect is called the ..................................................... effect.
(1)
(ii)What do the letters a.c. stand for?
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(1)
(iii)Name an instrument that could be used to measure the potential difference betweenXandY.
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(b)Graph 1shows the output from the a.c. generator.
Graph 1
(i)One of the axes onGraph 1has been labelled Potential difference.
What should the other axis be labelled?
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(1)
(ii)The direction of the magnetic field is reversed.
OnGraph 1, draw the output from the a.c. generator if everything else remains the same.
(2)
(iii)The output from the a.c generator is changed to be half-wave rectified.
Draw the half-wave rectified output onGraph 2.
Graph 2
(2)
(iv)State the name of a component that may be used for the half-wave rectification of a.c.
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(1)
(c) The number of turns of wire on the coil is increased. This increases the maximum induced potential difference.
Statetwoother ways in which the maximum induced potential difference could be increased.
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(2)
(Total 11 marks)
Q2.(a) A resistor is a component that is used in an electric circuit.
(i)Describe how a student would use the circuit to take the readings necessary to determine the resistance of resistorR.
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(6)
(ii)Explain why the student should open the switch after each reading.
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(2)
(iii)In an experiment using this circuit, an ammeter reading was 0.75 A.The calculated value of the resistance of resistorRwas 16 .
What is the voltmeter reading?
Use the correct equation fromSection Cof the Physics Equations Sheet.
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Voltmeter reading = ................................ V
(2)
(iv)The student told his teacher that the resistance of resistorRwas 16 .
The teacher explained that the resistors used could only have one of the following values of resistance.
10
12
15
18
22
Suggest which of these resistors the student had used in his experiment.
Give a reason for your answer.
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(2)
(b) The diagram shows a fuse.
Describe the action of the fuse in a circuit.
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(3)
(Total 15 marks)
Q3.The diagrams show oscilloscope traces. Three different alternating current (a.c.) electricity supplies,J,KandL, produce these traces.
In each diagram, one vertical division on the oscilloscope screen represents 2 volts.
(a) Whichoneof the electricity supplies,J,KorL, has the largest peak potential difference?
Write your answer,J,KorL, in the box.
(1)
(b) Calculate the value of the largest peak potential difference.
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Largest peak potential difference = ................................... V
(1)
(c) The oscilloscope is now connected across a 3 V battery. The battery supplies direct current (d.c.). The settings on the oscilloscope arenotchanged.
On the diagram below draw the trace you would see on the oscilloscope screen.
(2)
(Total 4 marks)
Q4.(a)The diagram shows the inside of a three-pin plug.
(i)What name is given to the wire labelledS?
Draw a ring around the correct answer.
earth
live
neutral
(1)
(ii)What is the colour of the insulation around the wire labelledT?
Draw a ring around the correct answer.
blue
brown
green and yellow
(1)
(b) The plug contains a 13 amp fuse.
(i)Whichoneof the following is the correct circuit symbol for a fuse?
Draw a ring around the correct answer.
(1)
(ii)The diagram shows the parts of the fuse.
What would happen if a current of 20 amps passed through the 13 amp fuse?
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(1)
(c) Not all electrical appliances are earthed.
(i)Whichoneof the following appliances must be earthed?
Tick ()onebox.
Table lamp
Toaster
Hair straighteners
Give a reason for your answer.
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