A person walks across a nylon carpet wearing rubber-soled shoes. When they then touch a metal door handle, they feel a small electric shock. Explain why the person receives an electric shock when they touch the door handle.

OCR GCSE Physics A: Gateway Science (J249) — P3.1 Static and charge · Explain · 4 marks · View as Markdown

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

Nylon carpets and rubber-soled shoes are both electrical insulators. Metal door handles are electrical conductors.

Model answer (4 marks)

Friction between the rubber soles and the nylon carpet transfers electrons, leaving the person with a net static charge. The rubber soles and carpet are insulators, so the charge cannot escape. When the person touches the metal door handle, the charge flows through the conductor, producing a small electric shock.

Examiner tips

  • Use the word ‘friction’ and ‘electrons’ to show cause; mention the insulator property; explain the flow of charge on contact; keep answer concise and to the point.

Common mistakes

  • Confusing the carpet with the person as the charge holder; not mentioning the insulator property; describing the shock as a chemical reaction instead of current flow.

Mark scheme (4 marks)

  1. Friction between the shoes and the carpet causes electrons to be transferred
  2. Electrons transfer to (or from) the person, leaving the person with a net (static) charge
  3. The charge cannot flow away because the rubber soles / nylon carpet are insulators
  4. When the person touches the metal handle, charge flows (as a current) through the conductor, causing the shock

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