Electric Charge

Electrical By : Aries Triwidajati S. SPd SMP Negeri 2 Cileunyi

Measurements • • • •

The Electroscopes Pith ball Metal foil Large metal foil

Materials 1. Conductors 2. Insulators 3. semi-Conductors

Conduction • When negatively charged electroscope is touched by a hand ... Describe the exchange of charge. – Electrons are repelled by the same charge – The hand (ground) removes electrons by conduction. – As the hand is removed, the neutral charge is uniformly distributed – The hand and electroscope have

Charging by Conduction and Induction • When negatively charged balloon is brought near electroscope, Describe the change in charges. – Electrons are repelled by the same charge – The leaves repel each other with the same charge (conduction) – The hand (ground) removes electrons by conduction. – As the balloon is removed, the positive charge uniformly distributed – The balloon and electroscope have opposite charges after the induction

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Charging by Conduction and Induction • Suppose a negatively charged balloon is brought close to one of the two identical insulated metal spheres. Describe the change in charge. – Electrons from the first sphere will be pushed onto the sphere farther from the balloon ......What charge will each sphere get? • the first sphere positively charged • the second sphere negatively charged – If the spheres are then separated, how does the charge change?

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Summary • There are four charged conditions: Negative, Positive, Neutral, and Ground • Conduction distributes the same charge to all objects. • Induction will leave an opposite charge. • Induction can charge objects through use of a ground. 7

Static Electricity Worksheet • Name ________________________________ • Form ________________________________ • Date

Draw a diagram and explain, using the charge model of electricity, the effect observed in the following situations.

Sticky Balloon Rub an inflated balloon quickly up and down on a smooth wall for ten seconds and then release your grip. __________________________________ __________________________________ __________________________________ __________________________________ __________________________________