Static electricity

Rubbing some materials together moves electrons from one to the other, leaving them charged. Like charges repel and unlike charges attract.

Key facts

  • Only electrons move. Gaining electrons gives a negative charge; losing them gives a positive charge.
  • Like charges repel, unlike charges attract.
  • Charged objects can attract uncharged ones by induction.
  • Sparks happen when charge jumps through the air.

Worked examples

Example 1

A polythene rod rubbed with a cloth becomes negative. What happens to the cloth?

  1. Electrons moved from the cloth to the rod.
  2. The cloth lost electrons, so it’s positive.

Answer: It becomes positive