# Physics 10 Notes on Static Electricity.

Essay by penginHigh School, 10th grade September 2004

Static Electricity

Bohr Model

Electrons move

External

Less massive compared to protons (2000x)

Charges

Positive

Objects gain (+) by loosing electrons

Negative

Object gain (-) by gaining electrons

Coulombs

Measures Charges

Millikan

Elementary charge

e = 1.6 x 10 -19

smallest found in electron / proton

Total Charge

Q = ne

n is charge (# electrons / protons)

e is elementary charge

Forces

Opposites attract

Like charge repel

Charged & neutral attract

Polarization

e are repelled or attracted

Charging Objects

Contact

Friction

2 dissimilar materials rub 2gether

1 has affinity for electrons

1 wants to give electrons

Induction

Charged object comes close to another neutral object that is connected to ground

Charged objected rebels electrons into the groun

Connection to ground is broken

End result is charged object

Electrical Ground

Any charged objects that come in contact w/ the ground will be neutralized

Little difference to net charge

It's BIG

Plumbing

Bill Gates finding 25 cents

Twitches

Causes twitch

Non Conductors

Dielectric property

Ability to keep charges separate

Electricity will go thru it

Provided w/ enuf voltage

Electricity

Will always find the path least resistant (easiest)

Air is hard

Ben Franklin

Invented lightening rod

Vandegraff generator

Plastic Rollers rub against belt

Frictional charging occurs (at the bottom..

motor)

Polarization causes the belt charges to separate neutral to (+) to neutral to (-)

Plastic rollers is slightly (+)

Gets (-) from brush

Electrons attracted to (+) charge on belt

Ground supplies more (-)

Electrons fly off into dome at top

Electro field

Repulsion

(-) evenly spread out apart dome

Repulsion

Goes to outermost

Sparks

Too many (-)

Needs to discharge

Coulomb's Law

Calculates forces btwn 2 charged objects

F= (kq1q2)/r2

Q=ne

K = constant

9 x 109 Nm2/C2