The Clingy Balloon

Why it matters

Rub a balloon on your hair and it clings to the wall, lifts paper bits and makes your hair stand up. You just moved a few billion electrons — and they stayed where you put them.

The idea in plain words

The static toolkit. Tap it.

like charges repel · unlike attract

Why do the electroscope's leaves move apart when charged?

They push each other apart — the divergence measures the charge

• the name: static — charges at REST on a surface — unlike current, which flows
• the instrument: electroscope — two thin leaves that repel and diverge when charged — a charge detector
• the big version: lightning & conductor — clouds charge by friction; a lightning conductor guides the strike safely to earth
• Both leaves receive the SAME kind of charge
• Like charges repel

Predict first

Rubbing a balloon on hair charges it by…

Charge is never created — only MOVED. The balloon steals electrons from your hair; both become charged, oppositely. (Conservation of charge.)

• transferring electrons between hair and balloon — correct
• creating new charge from friction
• heating it up

What you do

Rub up a good charge, lift the paper bits, watch the electroscope leaves spread — then touch it and lose everything to earth.

Check yourself

Two balloons both rubbed on hair, brought near each other, will…

Same treatment, same charge, mutual repulsion — the sure test of charging.

A lightning conductor protects a building by…

Copper strip, spiked top, buried plate — the strike takes the expressway instead of the walls.

Crackling sounds when removing a woollen sweater in winter are caused by…

Friction charged you and the sweater — separation lets the charge jump back, snap by snap.

• repel — they carry the same kind of charge — correct
• attract
• pop
• offering the strike an easy, safe path to the earth — correct
• repelling the clouds
• absorbing the lightning into the metal
• tiny sparks of static discharge — correct
• the fabric tearing
• cold air snapping