Restless Electrons

4.1.2 Transfer of Charge

Good Conductor/Poor Insulator

Allows electrons to flow freely.

Good Insulator/Poor Conductor

Strongly resists flow of electrons.

Conductive Properties of Materials

HIGH CONDUCTIVITY LOW CONDUCTIVITY LOW RESISTIVITY HIGH RESISTIVITY

Charging by Friction• Rub two insulators together

• ELECTRONS move from one to the other• One object becomes + the other -

RULE #1 – ONLY ELECTRONS MOVE

- - - - -

-

-

-

-

Grounding Symbol:

Grounding

• Since the Earth is very large it can neutralize:• negative objects by

ABSORBING electrons• positive objects by

RELEASING electrons

++++

RULE #2 – GROUNDING MAKES ANOBJECT NEUTRAL

2

+ -

1

+ - - +

3

+ - - +

- - - - - - - - --

-

-

-

--

-

-

-

-

-

--

--+

Induction – Negative Rod

ANIMATENEXT

RULE #3 – ELECTRONS FLOW TOWARD LESS NEGATIVE/MORE POSTIVE AREAS

Induction – movementof charge without

contact

3

+ -- +

2

- +

1

+ -- +

+ + + + + + + -

-

-

-

-

--

-

-

-

-

-

--

-

-

Induction – Positive Rod

ANIMATENEXT

RULE #4 – INDUCTION = POLARIZATION

Induction – movementof charge without

contact

3

-

2

-

e-1

+ -- +

---

--

-- -

Conduction – Negative Rod

- - - - - - - - - - -

ANIMATENEXT

Conduction – movementof charge with

contact

RULE #5 – CHARGING BY CONDUCTION GIVES SAME

CHARGE

3

+

2

+

e--

-

-

-

-

-

-

-

Conduction – Positive Rod

+ + + + + + + + +

ANIMATENEXT

Conduction – movementof charge with

contact

RULE #5 – CHARGING BY CONDUCTION GIVES SAME

CHARGE1

+ -- +

The Electroscope

- -

UNCHARGED CHARGED

LEAVES

- - - - - - - - - - - -

Induction – Negative Rod

ANIMATENEXT

-

e-e-1

RULE #4

2+

--e-

3

3

+ + + + + + + + +

Induction – Positive Rod

ANIMATENEXT

-

e-e-

RULE #4

12-

++e-

2-

--

e- -

--

3-

--

ANIMATENEXT

-

- - - - - - - - - - - -e -

e -

Charging by Conduction – Negative Rod

RULE #5

4

e-

51

52-

--

e- +

++

3+

++

14

e-

Charging by Conduction – Positive Rod

ANIMATENEXT

-

+ + + + + + + + + e -

e -

RULE #5

6

e-

213+ e-

+ +

4+

++

Charging by Induction – Negative Rod

ANIMATENEXT

-

- - - - - - - - - - - -

e -e -

RULE #6

5+

++

6

e-

213- e-

- -

4-

--

Charging by Induction – Positive Rod

ANIMATENEXT

-

+ + + + + + + + +

e -e -

RULE #6

5-

--

RULE #6 – CHARGING BY INDUCTION GIVES OPPOSITE

CHARGE

End of 5.1.2 - PRACTICE