CIE A Level Physics

Topic Questions

Syllabus Edition

First teaching 2020

Last exams 2024

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10.1 DC: Practical Circuits & Kirchhoff's Laws

11 mark

A battery is marked 9.0 V.

What does this mean ?

  • each coulomb of charge from the battery supplies 9.0 J of electrical energy to the whole circuit

  • the battery supplies 9.0 J to an external circuit for each coulomb of charge

  • the potential difference across any component connected to the battery will be 9.0 V

  • there will always be 9.0 V across the battery terminals

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21 mark

Which symbol represents a component whose resistance is designed to change with temperature?

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31 mark

In the circuit shown, a light-dependent resistor (LDR) is connected to two resistors R1 and R2.

 The potential difference (p. d.) across R1 is V1 and the p .d. across R2 is V2. The current in the circuit is I .

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Which statement about this circuit is correct ?

  • the current I  increases when the light intensity decreases

  • the LDR is an ohmic conductor

  • the p .d. V2 increases when the light intensity decreases

  • the ratio  V subscript 1 over V subscript 2  is independent of light intensity

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41 mark

A cell of e. m .f. E delivers a charge Q to an external circuit.

 Which statement is correct?

  • the energy dissipation in the external circuit is EQ

  • the energy dissipation within the cell is EQ

  • the external resistance is EQ

  • the total energy dissipation in the cell and the external circuit is EQ

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51 mark

The principles of conservation of which two quantities are associated with Kirchhoff's first and second Laws?

 

First Law

Second Law

A

B

C

D

charge

charge

energy

voltage

energy

voltage

charge

charge

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61 mark

In deriving a formula for the combined resistance of three different resistors in series, Kirchhoff's Laws are used.

 Which physics principle is involved in this derivation ?

  • the conservation of charge

  • the direction of the flow of charge is from negative to positive

  • the potential difference across each resistor is the same

  • the current varies in each resistor, in proportion to the resistor value

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71 mark

A cell is connected to a resistor.

 At any given moment, the potential difference across the cell is less than its electromotive force.

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Which statement explains this ?

  • the cell is continually discharging

  • the connecting wire has some resistance

  • energy is needed to drive charge through the cell

  • power is used when there is a current in the resistor

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81 mark

The combined resistance RT of two resistors of resistances R1 and R2 connected in parallel is given by the formula

               1 over R subscript T equals 1 over R subscript 1 plus 1 over R subscript 2

Which statement is used in the derivation of this formula?

  • the currents through the two resistors are equal

  • the potential difference across each resistor is the same

  • the supply current is split between the two resistors in the same ratio as the ratio of their resistances

  • the total power dissipated is the sum of the powers dissipated in the two resistors separately

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91 mark

Each of Kirchhoff's two Laws presumes that some quantity is conserved.

 Which row states Kirchhoff's first Law and names the quantity that is conserved ?

 

 

Statement

Quantity

A

The algebraic sum of currents into a junction is zero

charge

B

The algebraic sum of currents into a junction is zero

energy

C

The e. m. f. in a loop is equal to the algebraic sum of the product of current and resistance around the loop

charge

D

The e .m .f. in a loop is equal to the algebraic sum of the product of current and resistance around the loop

energy

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101 mark

Four statements about potential difference or electromotive force are listed. 

1

It involves changing electrical energy into other forms

2

It involves changing other energy forms into electrical energy

3

It is the energy per unit charge to move charge right round a circuit

4

It is the work done per unit charge by the charge moving from one point to another

 

Which statements apply to potential difference and which apply to electromotive force?

 

 

Potential difference

Electromotive force

A

B

C

D

1 and 3

1 and 4

2 and 3

2 and 4

2 and 4

2 and 3

1 and 4

1 and 3

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11 mark

A power supply of electromotive force (e .m .f.) 12 V and internal resistance 2 Ω is connected in series with a load resistor. The value of the load resistor is varied from 0.5 Ω to 4 Ω.

 Which graph shows how the power P dissipated in the load resistor varies with the resistance of the load resistor ?

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21 mark

Six resistors, each of resistance 5 Ω, are connected to a 2 V cell of negligible internal resistance.

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What is the potential difference between terminals X and Y ?

  • 2 over 3 space V

  • 8 over 9 space V

  • 4 over 3 space V

  • 2 space V

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31 mark

A relay is required to operate 800 m from its power supply. The power supply has negligible internal resistance. The relay requires 16.0 V and a current of 0.60 A to operate.

 A cable connects the relay to the power supply, and two of the wires in the cable are used to supply power to the relay.

 The resistance of each of these wires is 0.0050 Ω per meter.

 What is the minimum output e .m .f. of the power supply ?

  • 16.6 V

  • 18.4 V

  • 20.8 V

  • 29.3 V

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41 mark

Four resistors of equal value are connected as shown.

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How will the powers to the resistors change when resistor W is removed?

  • the powers to X, Y and Z will all increase

  • the power to X will decrease and the powers to Y and Z will increase

  • the power to X will increase and the powers to Y and Z will decrease

  • the power to X will increase and the powers to Y and Z will remain unaltered

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51 mark

The diagram shows a four-terminal box connected to a battery and two ammeters.

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The currents in the two meters are identical.

 Which circuit, within the box, will give this result ?

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61 mark

A p. d. of 12 V is connected between P and Q.

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What is the p. d. between X and Y?

 

  • 0 V

  • 4 V

  • 6 V

  • 8 V

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71 mark

The diagram shows the circuit for a signal to display a green or a red light. It is controlled by the switch S.

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The signal is some way from S to which it is connected by a cable with green, red and black wires. At the signal, the green and red wires are connected to the corresponding lamp and the black wire is connected to a terminal x to provide a common return. The arrangement is shown correctly connected and with the switch set to illuminate the red lamp.

 During maintenance, the wires at the signal are disconnected and, when reconnected, the black wire is connected in error to the green lamp (terminal g) instead of terminal x. The red wire is connected correctly to its lamp and connections at S remain as in the diagram.

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When the system is tested with the switch connection to the red wire, what does the signal show ?

  • the green lamp illuminated normally

  • the red lamp illuminated normally

  • the red and green lamps both illuminated normally

  • the red and green lamps both illuminated dimly

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81 mark

A box with four terminals P, Q, R and S contains two identical resistors.

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When a battery of electromotive force (e .m. f.) E and negligible internal resistance is connected across PS, a high-resistance voltmeter connected across QR reads  E over 2  

 Which diagram shows the correct arrangement of the two resistors inside the box ?

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91 mark

A 20 V d. c. supply is connected to a circuit consisting of five resistors L, M, N, P and Q.

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There is a potential drop of 7 V across L and a further 4 V potential drop across N.

 What are the potential drops across M, P and Q?

 

 

Potential drop across M / V

Potential drop across P / V

Potential drop across Q / V

A

B

C

D

9

13

13

17

7

7

11

3

13

13

9

17

 

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101 mark

The diagram shows the electric motor for a garden pump connected to a 24 V power supply by an insulated two-core cable.

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The motor does not work so, to find the fault, the negative terminal of a voltmeter is connected to the negative terminal of the power supply, and its other end is connected in turn to terminals X and Y at the motor.

 Which row represents two readings and a correct conclusion?

 

 

Voltmeter reading when connected to X / V

Voltmeter reading when connected to Y / V

 

Conclusion

A

B

C

D

24

24

24

24

0

12

24

24

break in positive wire of cable

break in negative wire of cable

break in connection within the motor

break in negative wire of cable

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11 mark

A cell of e .m .f. 2.0 V and negligible internal resistance is connected to a network of resistors as shown.

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What is the current I ?

  • 0.25 A

  • 0.33 A

  • 0.50 A

  • 1.5 A

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21 mark

A battery of e .m .f. 12 V and internal resistance 2.0 Ω is connected in series with an ammeter of negligible resistance and an external resistor. External resistors of various different values are used.

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Which combination of current and resistor value is not correct?

 

 

Current / A

External resistor value / Ω

A

B

C

D

1.0

1.2

1.5

1.8

10.0

8.0

6.0

4.0

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31 mark

The diagram shows part of a current-carrying circuit. The ammeter has negligible resistance.

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What is the reading on the ammeter ?

  • 0.7 A

  • 1.3 A

  • 1.5 A

  • 1.7 A

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41 mark

In the circuit shown, all the resistors are identical.

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The reading on voltmeter V1 is 8.0 V and the reading on voltmeter V2 is 1.0 V. What are the readings on the other voltmeters?

 

 

Reading on voltmeter V3 / V

Reading on voltmeter V4 / V

A

B

C

D

1.5

3.0

4.5

6.0

1.0

2.0

3.0

4.0

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51 mark

A cell, two resistors of equal resistance and an ammeter are used to construct four circuits. The resistors are the only parts of the circuits that have resistance.

 In which circuit will the ammeter show the greatest reading ?

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61 mark

The diagram shows a circuit with four voltmeter readings V, V1, V2 and V3.

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Which equation relating the voltmeter readings must be true?

  • V = V1 + V2 + V3

  • V + V1 = V2 + V3

  • V3 = 2(V2)

  • VV1 = V3

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71 mark

A simple circuit is formed by connecting a resistor of resistance R between the terminals of a battery of electromotive force (e .m .f.) 9.0 V and constant internal resistance r .

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A charge of 6.0 C flows through the resistor in a time of 2.0 minutes, causing it to dissipate 48 J of thermal energy.

 What is the internal resistance r of the battery ?

  • 0.17 Ω

  • 0.33 Ω

  • 20 Ω

  • 160 Ω

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81 mark

When four identical resistors are connected as shown in diagram 1, the ammeter reads 1.0 A, and the voltmeter reads zero.

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The resistors and meters are reconnected to the supply, as shown in diagram 2.

 What are the meter readings in diagram 2?

 

 

Voltmeter reading / V

Ammeter reading / A

A

B

C

D

0

3.0

3.0

6.0

1.0

0.5

1.0

0

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91 mark

The diagram shows currents I 1, I 2, I 3, I 4 and I 5 in different branches of a circuit.

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Which one of the following is correct?

  • I 1 = I 2 + I 3

  • I 2 = I 1 + I 3

  • I 3 = I 4 + I 5

  • I 4 = I 5 + I 3

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101 mark

In the circuit shown, all the resistors are identical and all the ammeters have negligible resistance.

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The reading on ammeter A1 is 0.6 A.

 What are the readings on the other ammeters?

 

 

Reading on ammeter A2 / A

Reading on ammeter A3 / A

Reading on ammeter A4 / A

A

B

C

D

1.0

1.4

1.8

2.2

0.3

0.6

0.9

1.2

0.1

0.2

0.3

0.4

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