1. Who’s right?
A metal is always charged because its free electrons can run around
In a metal both the positive and the negative charges will move
If you put a positively charged rod near the wires their free electrons will move towards the rod
If you put a positively charged rod near the wires their positive charges will be pushed away from the rod

2. Measuring electrostatic charges
Gold leaf electroscope
Charging an electroscope

3. The gold leaf electroscope
The charged acetate rod is too far, so the electroscope is uncharged
Metal plate
Acetate rod
Copper wire
Gold leaves
Click to see animation

5. The gold leaf electroscope
The charged acetate rod is close to the metal plate, so the electrons move to the metal plate and the gold leaves repel each other because full of positive charges. The electroscope is charged by induction.
Acetate rod
Metal plate
Copper wire
Gold leaves

6. Charging an electroscope
Explain in detail what is happening in these situations.
Remember…
opposite charges attract and like charges repel
the charges distribute around the surface of a metal
Only electrons (negative charges) are free to move, never positive charges
the effects of a negative and a positive charge close together cancel out (neutral)
Charged metal ball
Insulating handle
Click to see animation

8. Draw the position of the gold leaves and the distribution of charges in the following situations.

9. Draw the position of the gold leaves and the distribution of charges in the following situations.

10. Draw the position of the gold leaves and the distribution of charges in the following situations.

11. Draw the position of the gold leaves and the distribution of charges in the following situations.