Static Electricity

Static Electricity  History

of charged particles – 1900’s  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 Electricity Protons are never transferred!!! Charges are never created nor destroyed. = Conservation of Charge

JOKE #1

Ion

– “I think I’ve lost an electron.” Atom – “Are you sure?” Ion – “I’m 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 eRub

a glass rod with silk – the silk gains e- and the glass loses e-

Rub

a rubber rod with fur – the fur loses e- and the rod gains e-

They

will be oppositely charged and therefore attract each other.

Charging by Contact

HITT –Rub a Balloon in your hair. Can you tell it’s 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

– electrons are easily

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

Charging by Contact

Conduction  If

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

 Like

charges REPEL  Demo- Rub balloon in your hair!

If

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

LIKES

REPEL

OPPOSITES

ATTRACT

Demos 1.

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

Conduction is just like sharing To

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) Both –10

B)C) Both –5

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

+5

0

+5

DEB -10

-14

-10

-14

-12

-12

HITT +10

+14

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

B) right, left

+10

+12

+14

+12

HITT +10

-14

HITT Final Charge after sharing is B)–24

B) –12

C) –2

D) +2

+10

-14

-2

-2

Sharing when objects are not the same size.

-10 0

Sharing ?

-

0

-

-

-10

-

-

-

Grounding Sharing

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.

Induction Charging

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

HW – Case #2

t = 5 sec

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 Generator vandegraaf incaction

Demos with the VDG 1.

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

Lightning Where

is the safest place in a lightning storm?