Explain why a charged plastic rod can attract small pieces of paper, even though the pieces of paper are not charged.

Eduqas GCSE Physics — 7.3 Static electricity – forces and electric fields · Explain · 4 marks · View as Markdown

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

A student rubs a plastic rod with a cloth. The rod becomes negatively charged. When the rod is held close to small pieces of paper resting on a desk, the paper is attracted towards the rod.

Model answer (4 marks)

The negatively charged rod creates an electric field around it.
The field exerts a force on the electrons in the paper, pushing them away from the side nearest the rod.
This leaves the near side of the paper positively charged (induced charge).
Opposite charges attract, so the paper is pulled towards the rod.

Examiner tips

  • Use the word ‘electric field’ early; explain electron movement and induced charge; finish with attraction due to opposite charges; keep answer concise and to the point.

Common mistakes

  • Forgetting to mention the induced positive charge; confusing the direction of electron movement; using vague terms like ‘force’ without linking to the field.

Mark scheme (4 marks)

  1. The negative rod produces an electric field around it
  2. The electric field causes electrons in the paper to move / be repelled away from the side nearest the rod
  3. The side of the paper closest to the rod becomes positively charged (induced charge)
  4. Opposite charges attract, so the paper is pulled towards the rod

Key terms in this question

attract

Related

More Static electricity – forces and electric fields questions

▶ Try answering this question with AI marking (free) →