Static Electricity History

of charged particles 1900s Electrons(-) in shells Protons(+) in nucleus Neutrons(0) in nucleus

Static Electricity

Only electrons may be lost or gained. Rub the object If the atom loses electrons, it will become + If the atom gains electrons, it will become

Static ElectricityProtons are never transferred!!! Charges are never created nor destroyed. =Conservation of Charge

JOKE #1

Ion

I think Ive lost an electron. Atom Are you sure? Ion Im positive.

JOKE #2

An

neutron walks into a bar and asks the bartender for a drink. The neutron asks, How much for the beer? The bartender replies, For you, NO CHARGE!

Rubbing to lose/gain eRub

a glass rod with silk the silk gains e- and the glass loses ea rubber rod with fur the fur loses e- and the rod gains e-

Rub

They

will be oppositely charged and therefore attract each other.

Charging by Contact

HITT Rub a Balloon in your hair. Can you tell its charge?A)

Test with an electroscope B) Check the Triboelectric Series C) See whether it sticks to the ceiling D) Observe how it reacts to a magnet E) All are correct

Conductors

transferred ex) metals Ag, Au, Cu Insulators electrons do not move from one location to another ex) wood, plastic, air Semiconductors some electrons are free to move ex) Si, Ge metalloids

electrons are easily

Charging by Contact

Conduction If

two objects touch, they will have the same charge and REPEL (unless they wereneutral)

Like

charges REPEL Demo- Rub balloon in your hair!

If

two objects have the opposite charge, they will attract each other. REPEL ATTRACT

LIKES

OPPOSITES

Demos1.

Paper & Golf Tube 2. Golf Tube & 2 x 4 x 8 3. Balloon on the Wall

Conduction is just like sharingTo

charge an object by touching it with another charged object. The second object shares the charge and is always the same charge as the first object. Examples of sharing

HITT -10 0

A) Both 0 B)C) Both 5

B) Both 10 D) Both +5

-10

0

-5

-5

HITT +10 0

HITT In which direction do the electrons move A) Left B) Right C) Neither D) Both

+10

0

+5

+5

DEB -10 -14

-10

-14

-12

-12

HITT +10HITT Which sphere is more negative and in which direction do the electrons flow? C)right, right B) right, left

+14

+10

+14

+12

+12

HITT +10 -14

HITT Final Charge after sharing is B)24 C) 2 B) 12 D) +2

+10

-14

-2

-2

Sharing when objects are not the same size.

-10 0

Sharing ?

0

-

-

-

-10

-

GroundingSharing

charge between an extremely large object, like the EARTH, and a small object is called grounding. All the charge winds up in the earth and no charge is on the small object.

InductionCharging

by induction Case #1 - bring a negative object near Case #2 - bring a positive object near

Charging by Induction

t = 1sec

Charging by Induction

t = 2 sec

Charging by Induction

t = 3 sec

Charging by Induction

t = 4 sec

Charging by Induction

t = 5 sec

HW Case #2

Late at night, and without permission, Reuben often conducted experiments in static electricity! at night, and without

Balloons on the Ceiling Why

do balloons stick to the ceiling when rubbed on your hair?

Balloon on the Ceiling or Wall

Using a Van de Graaff Generatorvandegraaf incaction

Demos with the VDG1.

A hair raising experience 2. Packing pellets 3. Ribbon 4. Silver ball

LightningWhere

is the safest place in a lightning storm?