static electricity chapter 20. electric force section 20.1

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Static Electricity Chapter 20

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Page 1: Static Electricity Chapter 20. Electric Force Section 20.1

Static ElectricityChapter 20

Page 2: Static Electricity Chapter 20. Electric Force Section 20.1

Electric ForceSection 20.1

Page 3: Static Electricity Chapter 20. Electric Force Section 20.1

ElectrostaticsElectric Statics that can be

collected and held in one place.

Page 4: Static Electricity Chapter 20. Electric Force Section 20.1

Charged ObjectsObject 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

Page 5: Static Electricity Chapter 20. Electric Force Section 20.1

A Microscopic View of ChargeAll 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

Page 6: Static Electricity Chapter 20. Electric Force Section 20.1

Conductors and InsulatorsElectric

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

Page 7: Static Electricity Chapter 20. Electric Force Section 20.1

Electric ForceSection 20.2

Page 8: Static Electricity Chapter 20. Electric Force Section 20.1

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.

Page 9: Static Electricity Chapter 20. Electric Force Section 20.1

ElectroscopeDevice used to

determine charge.◦ Metal knob

connected by a metal stem to two thin, lightweight pieces of metal foil.

Page 10: Static Electricity Chapter 20. Electric Force Section 20.1

Charging by Conduction

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

positive

Page 11: Static Electricity Chapter 20. Electric Force Section 20.1

Separation of Charge on Neutral Objects

Neutral object will have charges separate. ◦ Neutral object will be attracted to

the charged object.

Page 12: Static Electricity Chapter 20. Electric Force Section 20.1

Charging by InductionCharging an object without

touching ◦ Single object can be charged by

induction through grounding

Page 13: Static Electricity Chapter 20. Electric Force Section 20.1

Coulomb’s LawForce depends on

distance◦ F = 1/r2

Force depends on charge

◦ F= qAqB

Coulomb’s Law

◦ F= qAqB/ r2

Elementary Charge◦ Magnitude on electron:

1.60 X 10 -19 C◦ 1 C = 6.24 X 1018

electrons

Page 14: Static Electricity Chapter 20. Electric Force Section 20.1

Coulomb’s Law

Force in Newtons (N)

Coulomb’s constant: 9.0 X 109 Nm2/C2

Distance between ChargesIn Meters (m)

Charge in Coulombs (C) of object 1

Charge in Coulombs (C) of object 2