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Charge a metal ball and hang a tiny pith ball beside it. How far does the invisible push move it?
Electric Fields lab · Last updated: 16 October 2026
A metal ball is given an electric charge, and a tiny, light pith ball hangs on a thread beside it. Without any touch, the pith ball swings. You move it closer and further away to measure the invisible push.
What you'll discover
- Charged objects push or pull on each other without touching.
- Like charges repel and opposite charges attract.
- The force weakens quickly with distance: twice as far gives a quarter of the push.
The science in plain words
Everything is made of atoms, which contain positive protons and negative electrons. Usually these balance out. When an object gains extra electrons it becomes negatively charged; when it loses some it becomes positively charged. Rubbing a balloon on your hair does exactly this.
Charged objects push or pull on each other even across a gap. Two objects with the same kind of charge repel, and objects with opposite charges attract. The space around a charge where this push or pull acts is called its electric field. You cannot see it, but you can see its effects, such as a pith ball swinging away.
The force grows weaker with distance, and quickly. Double the distance and the force drops to a quarter; triple it and it drops to a ninth. This rule was measured by Charles-Augustin de Coulomb in the 1780s, and gravity follows the same pattern.
Static electricity explains why clothes cling after drying, why you sometimes get a small shock from a door handle and how lightning starts. Photocopiers and some paint sprayers use electric fields to place toner or paint exactly where it is needed.
Where it fits
- India, NCERT: Class 8 science, Chapter 5: Exploring Forces
- United States: Grades 6 to 8
- Next Generation Science Standards: MS-PS2-3, MS-PS2-5
Common questions
What is static electricity?
It is a build-up of electric charge on an object, usually from rubbing two materials together so that electrons move from one to the other. The charge stays put until it can escape.
Why do like charges repel?
Charges create electric fields around them. Two positive or two negative charges push each other away, while a positive and a negative charge pull together. This is a basic rule of nature.
Does the electric force get weaker with distance?
Yes. It follows an inverse square law: at twice the distance the force is a quarter as strong, and at three times the distance it is a ninth as strong.
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- Storm over the Town: Where will the lightning strike? Watch it feel its way down, then add a lightning rod.
- Magnet and Compasses: Slide a magnet and compasses round a desk. Which way do the needles point, and why does a far one wobble slowly?
- Charge the Flash: Fill a capacitor from a battery. Why does the light start bright and then fade?
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Try it yourself
The Electric Fields lab is one of the interactive 3D science labs inside Taz. Change one thing, predict what will happen, then run it and watch. Labs open after you sign in.