ELECTRICITYCh. 20 Static Electricity

Ch. 21 Electric FieldsCh. 22 Current Electricity

Static Electricity Most things are neutral…..

• But electrons can be transferred causing a charge to occur temporarily.

• Opposites attract and Likes repel • More surface area, more electrons exposed• Lack electrons=+• Excess electrons= -

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Conductors-electrons move easily Insulators-electrons do not move

easily

Charging by Induction-charging over distance• Grounding-connecting to Earth to rid of excess electrons

Charging by Conduction-charging by touching• Electroscope• Stronger when closer

Coulomb’s Law Force depends on Distance Force depends on Charge Unit of charge-Coulomb Electron: 1.60 x 10-19 C 1 C=6.24 x 1018 electrons or protons

K=9.0x 109 Nm2/C2

Practice Sphere A, with a charge of +6.0 microC is located near

another charge sphere B. Sphere B has a charge of -3 microC and is located 4.0 cm to the right of A

A. What is the force of B on A:

100 N B. A third sphere C, with a +1.5 microC charge, is added to

the configuration. If it is located 3.0 cm directly beneath A, what is the new net force on sphere A?

130 N, 42 degrees SW

ELECTRIC FIELDS CH. 21 E=F on q/q2