A LevelPhysicsCIEExam Questions9. Electricity9.2 Potential Difference & Power

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First teaching 2023

First exams 2025

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Potential Difference & Power (CIE A Level Physics)

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9.2 Potential Difference & Power

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9.2 Potential Difference & Power

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1
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What describes the electric potential difference between two points in a wire that carries a current?

  • the force required to move a unit positive charge between the points

  • the ratio of the energy dissipated between the points to the current

  • the ratio of the power dissipated between the points to the current

  • the ratio of the power dissipated between the points to the charge moved

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2
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A filament lamp has a resistance of 180 Ω when the current in it is 500 mA.

 What is the power transformed in the lamp?

  • 45 W

  • 50 W

  • 90 W

  • 1400 W

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3
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A 12 V battery is charged for 20 minutes by connecting it to a source of electromotive force (e.m.f.). The battery is supplied with 7.2 × 104 J of energy in this time.

 How much charge flows into the battery?

  • 5.0 C

  • 60 C

  • 100 C

  • 6000 C

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4
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The diagram shows four heaters and the current in each.

 Which heater has the greatest power dissipation ?

cie-ial-physics-images-9-1-e-q8-

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    5
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    What is the correct definition for potential difference?

    • Energy transferred per unit charge

    • Energy transferred per unit current

    • Power transfer per unit charge

    • Work done per unit current

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    1
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    The diagrams show two different circuits.

    cie-ial-images428png

    The cells in each circuit have the same electromotive force and zero internal resistance. The three resistors each have the same resistance R.

     In the circuit on the left, the power dissipated in the resistor is P.

     What is the total power dissipated in the circuit on the right?

    • P over 4

    • P over 2

    • P

    • 2P

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    2
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    The potential difference across a component in a circuit is 2.0 V.

    How many electrons must flow through this component in order for it to be supplied with 4.8 J of energy?

    • 2.6 × 1018

    • 1.5 × 1019

    • 3.0 × 1019

    • 6.0 × 1019

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    3
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    Two lamps are connected in series to a 250V power supply. One lamp is rated 240V, 60W and the other is rated 10V, 2.5W.

     Which statement most accurately describes what happens ?

    • both lamps light at less than their normal brightness

    • both lamps light normally

    • only the 60 W lamp lights

    • the 10 V lamp blows

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    4
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    A power cable X has resistance R and carries current I.

     A second cable Y has resistance 2R and carries current I over 2

     What is the ratio fraction numerator p o w e r space d i s s i p a t e d space i n space Y over denominator p o w e r space d i s s i p a t e d space i n space X end fraction  ?

    • 1 fourth

    • 1 half

    • 2

    • 4

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    5
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    In a simple electrical circuit, the current in a resistor is measured as (2.50 ± 0.05) mA. The resistor is marked as having a value of 4.7Ω  ± 2 %.

     If these values were used to calculate the power dissipated in the resistor, what would be the percentage uncertainty in the value obtained?

    • 2 %

    • 4 %

    • 6 %

    • 8 %

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    6
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    A battery, with a constant internal resistance, is connected to a resistor of resistance 250 Ω, as shown.

    cie-ial-images430png

    The current in the resistor is 40 mA for a time of 60 s. During this time 6.0 J of energy is lost in the internal resistance.

     What is the energy supplied to the external resistor during the 60 s and the e.m.f of the battery ?

     

    Energy / J

    E. m. f / V

    A

    B

    C

    D

    2.4

    2.4

    24

    24

    2.4

    7.5

    10.0

    12.5

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      7
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      The charge that an electric battery can deliver is specified in ampere-hours.

       For example, a battery of capacity 40 ampere-hours could supply, when fully charged, 0.2 A for 200 hours.

       What is the maximum energy that a fully charged 12 V, 40 ampere-hour battery could supply ?

      • 1.7 kJ

      • 29 kJ

      • 1.7 MJ

      • 29 MJ

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      1
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      The amount of energy transferred when 10 C of charge passes through a p. d. of 20 V is the same as the energy needed to raise a 2 kg mass through a distance x.

       Take gravitational field strength to be 10 N kg–1.

       What is the value of x?

      • 0.1 m

      • 1.0 m

      • 10 m

      • 100 m

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      2
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      The ratings of two lamps are as follows:

       

      X

      230 V, 100 W

      Y

      230 V, 60 W

       

      During normal operation, which of the lamps will have larger current and resistance?

      • I subscript X greater than I subscript Y space a n d space R subscript X greater than R subscript Y

      • I subscript X greater than I subscript Y space a n d space R subscript X less than R subscript Y

      • I subscript X less than I subscript Y space a n d space R subscript X greater than R subscript Y

      • I subscript X less than I subscript Y space a n d space R subscript X less than R subscript Y

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      3
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      Two lightbulbs, X and Y, are in parallel and are attached to a cell which has a potential difference of 75 V. Lightbulb X has a resistance of 350 Ω and Lightbulb Y has a resistance of 500 Ω. The power of Lightbulbs X and Y are PX and PY respectively.

      What is the value of the ratio P subscript X over P subscript Y?

      • 1 half

      • 7 over 10

      • 10 over 7

      • 2

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      4
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      What is the effect on the current and power of a fixed resistor when the voltage through the resistor doubles?

       

      Current

       Power

      A.

      Quadruples

      Doubles

      B.

      Doubles

      Doubles

      C.

      Doubles

      Quadruples

      D.

      Halves

      Doubles

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        5
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        Two resistors, X and Y, are in series with a cell that has a potential difference of V. The resistance of X and Y is R and R over 2 respectively.

        Given that the charge through both resistors is 6 C, what is the power and work done of Resistor X?

         

        Power

        Work done

        A.

        2V

        		 fraction numerator 8 V squared over denominator 9 R end fraction

        B.

        3V

        		 fraction numerator V squared over denominator 2 R end fraction

        C.

        4V

        fraction numerator 4 V squared over denominator 9 R end fraction 

        D.

        6V

        		 V squared over R

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