Electric Forces

Science — First Preparatory

Applications and examples from life

Comparison aspect	Main idea	Keywords
A balloon sticking to a wall	rubbing a balloon on hair gives it a negative charge. It is attracted to the neutral wall by induction and it stays stuck to the wall	rubbinghairgivesnegative
Lightning	charges build up in clouds because water droplets and air rub against each other. When the charge becomes very large a spark jumps between the cloud and the ground	chargesbuildcloudsbecause
The electroscope	when a charged rod touches the metal top of an electroscope its two metal leaves receive the same charge and repel each other so they spread apart. The larger the charge the wider the leaves open	chargedtouchesmetalleaves

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