Questions

1. * Explain, with the aid of a circuit diagram, the method a student could use to investigate how
the resistance of a single lamp changes with the potential difference across the lamp. (6)
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(Total for question = 6 marks)

Q2.
(1)
A resistor is connected to a power supply.

The potential difference across the resistor is 6.0 V.

(i) Which of these corresponds to a potential difference of 6.0 V?

A 6.0 joules per ohm

B 6.0 amps per coulomb

C 6.0 joules per coulomb

D 6.0 amps per ohm

The current in the resistor is 200 mA.

A total charge of 42 C flows through the resistor.

Calculate, in minutes, the time taken for this amount of charge to flow through the resistor.

(3)

time = ........................................................... minutes

(iii) Calculate the total energy transferred by the 6.0 V power supply when a charge of 42 C
flows through the resistor.

(2)

energy = ........................................................... J

(Total for question = 6 marks)

Q3. Which of these symbols is used to represent a thermistor in an electrical circuit? (1)

Q4.

A student rubs a plastic comb with a dry cloth to give the comb a positive electric charge.

Figure 6 shows the charged plastic comb picking up small pieces of paper.
 Figure 6

(i) Explain how rubbing the comb with a dry cloth gives the comb a positive electric charge.

(3)

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(ii) Explain how the positively-charged plastic comb picks up the small pieces of paper.

(3)

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(Total for question = 6 marks)

Q5.

Figure 16 shows a cardboard tube with a wire coming out from each end.

Figure 16

There are two 10 ohm resistors inside the cardboard tube.

A potential difference of 6.0 V is connected between P and Q.

There is a current of 1.2 A in the wires.

Deduce how the resistors have been arranged inside the cardboard tube.
 (3)

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(Total for question = 3 marks)

A resistor is connected to a power supply.

The resistor becomes warm while there is a current in it.

Explain why the resistor becomes warm.

(2)

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(Total for question = 2 marks)

Q7.

* Figure 20 shows the three-pin plug used to connect the kettle to the mains.
A fault occurs in the kettle causing the live wire to touch the metal case of the kettle.

Explain how the safety features of the plug operate when this fault occurs.

(6)

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(Total for question = 6 marks)