Static Electricity Chapter 20

Electric Force Section 20.1

Electrostatics Electric Statics that can be collected and held in one place.

Charged Objects Object that exhibits electric interaction after rubbing is said to be charged ◦ Like charges: Repel each other ◦ Opposite charges: Attract each other ◦ Types of charge: Matter contains both charges

A Microscopic View of Charge All objects contain light, negatively charged particles ◦ Neutral object: positive charge of nucleus equals the negative charge of surrounding electrons ◦ Separation of charge: Occurs when two objects are rubbed together

Conductors and Insulators Electric Conductor ◦ Material that allows charges to move easily ◦ Metals (ie: copper, iron, silver, gold) Electric Insulator ◦ Material through which charge will not move easily ◦ Glass, dry wood, plastics, rubber, cloth, and dry air

Electric Force Section 20.2

Forces on Charged Bodies There are two kinds of charges: ◦ Positive and Negative Charges exert forces on other charges at a distance. The force is stronger when the charges are closer Like charges repel; opposite charges attract.

Electroscope Device used to determine charge. ◦ Metal knob connected by a metal stem to two thin, lightweight pieces of metal foil.

Charging by Conduction Charging a neutral body by touching it with a charged body ◦ Leaves spread apart it electroscope is positive

Separation of Charge on Neutral Objects Neutral object will have charges separate. ◦ Neutral object will be attracted to the charged object.

Charging by Induction Charging an object without touching ◦ Single object can be charged by induction through grounding

Coulomb’s Law Force depends on distance ◦ F = 1/r 2 Force depends on charge ◦ F= q A q B Coulomb’s Law ◦ F= q A q B / r 2 Elementary Charge ◦ Magnitude on electron: 1.60 X C ◦ 1 C = 6.24 X electrons

Coulomb’s Law Force in Newtons (N) Coulomb’s constant: 9.0 X 10 9 Nm 2 /C 2 Distance between Charges In Meters (m) Charge in Coulombs (C) of object 1 Charge in Coulombs (C) of object 2

The End!