GCSE-ready- Home
- Lessons
- KS3 Science
- Static electricity
Static electricity
🎬 The doodle video for this lesson is coming soon. Subscribe on YouTube to see it first.
Rub a balloon on your hair and it sticks to the wall. That is static electricity at work.
Charging by rubbing
Atoms contain tiny particles called electrons, which have a negative charge.
When two materials are rubbed together, electrons can move from one to the other.
The material that gains electrons becomes negatively charged. The one that loses electrons becomes positively charged.
Only electrons move. Positive charges stay where they are.
When two materials are rubbed together, electrons can move from one to the other.
The material that gains electrons becomes negatively charged. The one that loses electrons becomes positively charged.
Only electrons move. Positive charges stay where they are.
Forces between charges
Like charges repel (push apart): two negatives, or two positives.
Unlike charges attract: a positive and a negative.
These forces act without the objects touching: they are non-contact forces.
Unlike charges attract: a positive and a negative.
These forces act without the objects touching: they are non-contact forces.
Electric fields
A charged object has an electric field around it. Another charged object in that field feels a force.
The field is stronger closer to the charged object, so the force is bigger.
Static charge can build up and jump across a gap as a spark. Lightning is a giant spark from a charged cloud.
The field is stronger closer to the charged object, so the force is bigger.
Static charge can build up and jump across a gap as a spark. Lightning is a giant spark from a charged cloud.
A plastic rod is rubbed with a cloth and becomes negatively charged. Explain what happened.
- Rubbing moved electrons between the cloth and the rod.
- Electrons are negative.
- The rod gained electrons, so it became negative; the cloth lost electrons, so it became positive.
Answer: Electrons moved from the cloth to the rod, so the rod is negative and the cloth positive.
Rubbing moves electrons. Gaining electrons makes an object negative; losing them makes it positive. Like charges repel; unlike charges attract. A charged object has an electric field around it, and the force is stronger closer to it.
Check you have got it
Answer 6 quick questions with instant marking. If you get one wrong, GCSE-ready shows you why and gives you another go. It is free, and you do not need an account.