A technician is wiring the lights in a new house. She must decide whether to connect the lights in series or in parallel. Explain why connecting the lights in parallel is more suitable than connecting them in series for use in a house.

Eduqas GCSE Physics — 7.2 Series and parallel circuits · Explain · 4 marks · View as Markdown

Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).

Model answer (4 marks)

1. In a parallel circuit each lamp has its own branch, so it can be switched on or off independently.
2. If one lamp fails or is switched off, the other lamps remain lit because the circuit is not broken.
3. Each lamp in a parallel circuit receives the full supply voltage, giving the correct brightness.
4. In a series circuit the supply voltage is divided between the lamps, so they would be dimmer and a failure would take all lamps out.

Examiner tips

  • Use the word "parallel" and "series" clearly. Mention independent branches and full voltage. Show the consequence of a lamp failure. Keep each point short and to the point.

Common mistakes

  • Confusing the order of the points. Forgetting to mention the full voltage in parallel. Using vague terms like "better" without explaining why.

Mark scheme (4 marks)

  1. In a parallel circuit, each lamp has its own independent branch / switching off one lamp does not affect the others
  2. In a series circuit, if one lamp breaks/is switched off the circuit is broken and all lamps go out
  3. In a parallel circuit, each lamp receives the full supply voltage
  4. In a series circuit, the voltage is shared/divided between the lamps so they would be dimmer

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