# Chapter 20 Static Electricity

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Chapter 20 Static Electricity. Electrostatics - The study of electrical charges that can be collected and held in one place. Chapter 20 Static Electricity. Chapter 20 Static Electricity. - PowerPoint PPT Presentation

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• Chapter 20 Static ElectricityElectrostatics - The study of electrical charges that can be collected and held in one place.

• Chapter 20Static Electricity

ChargeSize

ProtonPositive1.67 x 10-27kgElectronNegative9.11 x 10-31 kgNeutronNeutral1.67 x 10-27 kg

• Chapter 20Static ElectricityEvery atom is composed of a positively charged nucleus, around which are distributed a number of negatively charged electrons.Electrons of all atoms are the same. Each has the same quantity of negative charge and the same mass.Protons and neutrons compose the nucleus. Protons are 2000 times more massive than an electron and carry an equal amount of charge.All normal atoms have equal number of protons and electrons.

• Chapter 20Static Electricity

• Chapter 20Static Electricity

• Chapter 20Static Electricity Charged versus Uncharged Objects

Positively-Charged Possesses more protons than electrons

Negatively-Charged Possesses more electrons than protons

Uncharged Equal numbers of protons and electrons

• Chapter 20Static ElectricityElectric Charge: Positive or negative Charge is quantified Like charges repel, opposites attract Charges exert a force through a distance. The force is stronger when the charges are close together

• Chapter 20Static Electricity

• Chapter 20Static Electricity

• Chapter 20Static Electricity

• Chapter 20Static ElectricityGrounding Connecting a charged object to earth to remove an objects charge.Conductor Any material through which an electric charge is readily transferred.Insulator Any material through which an electric charge is not readily transferred.Induction The process of charging an object by bringing it into the electric field of another object.

• Chapter 20Static Electricity

• Chapter 20Static Electricity

• Chapter 20Static ElectricityCharge by Conduction

• Chapter 20Static ElectricityCharge by Induction

• Chapter 20Static Electricity

• Chapter 20Static Electricity

• Chapter 20Static Electricity

• Chapter 20Static ElectricityCoulomb The quantity of electric charge

1 coulomb = 6.25 x 1018 electrons1 electron = 1.6 x 10-19 coulombs

• Chapter 20Static ElectricityCoulombs Law The force between two charged objects vary directly with the product of their charges and inversely as the square of the distances between them.F force (N)q charge (C)k 9 x 109 N m2/ C2 Inverse Square Law

• Chapter 20Static Electricity Find the force of attraction between charges of 100 C and -50 C separated by a distance of 50 cm.q1 = 1 x 10-4 Cq2 = -5 x 10-5 CD = .5 mk = 9 x 109 N m2/ C2

• Chapter 20Static Electricity Find the force of attraction between charges of 100 C and -50 C separated by a distance of 50 cm.F = -180 N The negative means a force of attraction

• Chapter 20Static Electricity Two charges are separated by 4.0 cm. Object A has a charge of +5 C and object B has a charge of +3 C. What is the force on object A?q1 = 5 x 10-6 Cq2 = 3 x 10-6 CD = .04 mk = 9 x 109 N m2/ C2

• Chapter 20 Static Electricity Two charges are separated by 4.0 cm. Object A has a charge of +5 C and object B has a charge of +3 C. What is the force on object A?F = 84 N The positive means a force of repulsion

• Chapter 20Static ElectricityA positive charge of 3.5 x 10-6 C has 2 charges nearby. One has a negative charge of -1.2 x 10-6 C and is .03 m away at 180. The second charge is a positive charge of 3 x 10-6 C at 270 at .02 m.

What is the total force on the 3.5 x 10-6 C charge?

• Chapter 20Static Electricity

• Chapter 20Static ElectricityF1 = 42 NF2 = 236 N

• Chapter 20Static ElectricityF2 = (42 N)2+ (236 N)2 = 57460F = 240 Ntan = 42 N/236 N = .178 = 10The force on the 3.5 x 10-6C is 240 N at 100

• Chapter 20Static ElectricityA negative charge of 4.5 C has 2 charges nearby. One has a negative charge of 1.2 C and is .04 m away at 90. The second charge is a negative charge of 2.1 C at 180 at .03 m.

What is the total force on the 4.5 C charge?

• Chapter 20Static Electricity

• Chapter 20Static ElectricityF2 = 30 NF1 = 95 N

• Chapter 20Static ElectricityF2 = (30 N)2+ (95 N)2 = 9736F = 99 Ntan = 30 N/ 95 N = .315 = 17The force on the 4.5 C is 99 N at 343-30 N95 N