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Chapter 4 Practice Paper: Mains electricity and the National Grid — question paper

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QQ/GCSE-PHYS/CH4

GCSE (9–1) · GCSE Physics (Foundation and Higher)

Chapter 4 Practice Paper

Mains electricity and the National Grid

Duration: 40 minutes
Total: 30 marks
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READ THESE INSTRUCTIONS FIRST

  • Answer all questions.
  • Section A contains ten multiple-choice questions. Choose one answer, A, B, C or D, for each.
  • Section B contains structured questions. Write your answers in the spaces provided.
  • You may use a calculator.
  • The number of marks is given in brackets [ ] at the end of each question or part question.
  • The total mark for this paper is 30.

Original practice material written for the MOE GCSE Physics syllabus. It is not an official MOE or school examination paper. Chapter 4: a.c. and d.c., UK mains wiring, fuses and earthing, P = V I and P = I² R, energy in kWh, the National Grid at high voltage, and static electricity (Physics only).

For Examiner’s Use
Section A/ 10
Section B/ 20
Total/ 30

Section A: Multiple-choice questions[10 marks]

Choose one answer for each question. Each question is worth 1 mark.

  1. 1

    UK mains supplies alternating current with a frequency of

    1. A230 Hz
    2. B50 Hz
    3. C5 Hz
    4. D50 000 Hz
    ( )
  2. 2

    Direct current means the charge flows

    1. Ain one direction only
    2. Bbackwards and forwards
    3. Cin circles
    4. Dupwards only
    ( )
  3. 3

    The earth wire is coloured

    1. Abrown
    2. Bblue
    3. Cgreen and yellow
    4. Dwhite
    ( )
  4. 4

    A fuse protects an appliance by

    1. Areducing the voltage
    2. Bstoring spare charge
    3. Ccooling the cable
    4. Dmelting and breaking the circuit when the current is too large
    ( )
  5. 5

    An electric fire takes 8.0 A from the 230 V mains. The best fuse from the standard ratings is

    1. A1 A
    2. B3 A
    3. C13 A
    4. D5 A
    ( )
  6. 6

    A transmission cable of resistance 0.50 Ω carries 60 A. The power wasted as heat is

    1. A30 W
    2. B120 W
    3. C180 W
    4. D1 800 W
    ( )
  7. 7

    The National Grid uses high transmission voltages mainly to

    1. Aincrease the current
    2. Breduce heating losses in the cables
    3. Cmake electricity travel faster
    4. Dcharge the transformers
    ( )
  8. 8

    Rubbing an insulator charges it by

    1. Acreating electrons
    2. Bremoving its protons
    3. Ctransferring electrons to or from another surface
    4. Dheating it
    ( )
  9. 9

    A negatively charged rod is held near a negatively charged sphere. They

    1. Aattract
    2. Brepel
    3. Ccancel out
    4. Ddo nothing
    ( )
  10. 10

    Double-insulated appliances do not need an earth wire because

    1. Atheir plastic cases cannot become live
    2. Bthey run on batteries
    3. Cthey use no fuse
    4. Dthey work at low voltage only
    ( )

Section B: Structured questions[20 marks]

Answer all questions in the spaces provided.

  1. 11

    A washing machine is labelled 2 300 W, 230 V and has a metal case connected to the earth wire.

    1. (a)

      Calculate the current it draws in normal use.

      [2]
    2. (b)

      Choose its fuse from 3 A, 5 A and 13 A.

      [1]
    3. (c)

      The live wire breaks and touches the metal case. Explain how the earth wire and fuse respond.

      [2]
  2. 12

    This question is about the National Grid.

    1. (a)

      A cable of resistance 2.0 Ω carries 30 A. Calculate the power wasted as heat.

      [2]
    2. (b)

      The same power is delivered at ten times the voltage, so the current falls to 3.0 A. Calculate the new loss.

      [2]
    3. (c)

      State the factor by which the loss has fallen.

      [1]
    4. (d)

      Name the device that raises the voltage for transmission and the device that lowers it near homes.

      [2]
    5. (e)

      Give two reasons the transmission voltage is never supplied to homes.

      [2]
  3. 13

    This question is about static electricity (Physics only). A photocopier uses charged toner powder, and an aircraft is earthed before refuelling.

    1. (a)

      Explain how the toner can be attracted to a charged imaging drum.

      [2]
    2. (b)

      Explain why the aircraft must be earthed before refuelling.

      [2]
    3. (c)

      State how the electric field around the charged drum changes with distance.

      [2]

— End of paper —