There are three main types of electroscopes: 1) A pith ball electroscope uses a nonconductive string to suspend a ball that will swing in response to nearby charges. 2) A metal leaf electroscope has two thin metal leaves attached to a conductive rod, which will move apart when a charge is placed on the rod. 3) A needle electroscope has a pivoted needle on either side of a conductive bar; when a charge is placed on the bar, the needle will swivel away as the bar and needle take on the same charge. Electroscopes are used to detect static electric charges.

1. Electroscopes
1

2. Electroscopes
An electroscope is a device that is used to
detect a static charge.

3. Electroscopes
There are 3 kinds of electroscopes we will see:
1) Pith ball electroscope
2) Metal leaf electroscope
3) Needle electroscope

4. Pith Ball Electroscope
1) The pith ball electroscope is a ball connected to a
stand using a nonconductive string.

5. Pith Ball Electroscope
Nonconductive
string
Ball

6. Pith Ball Electroscope
The ball is able to swing in any and all directions in
response to nearby charges.

7. Metal Leaf Electroscope
2) A metal leaf electroscope is a vertical conductive
rod with a metal ball on top and 2 thin sheets of
loose metal attached at the bottom.

8. Metal Leaf Electroscope
Touch ball
Conductive bar
Metal leaves

9. Metal Leaf Electroscope
If a charge contacts the touch ball then both leaves will
receive this charge and move apart.
Neutral Charged

10. Metal Leaf Electroscope
Copy this example into your notes.
Neutral Charged

11. Needle Electroscope
3) A needle electroscope has a touch ball attached to a
conductive bar that bends. There is a pivoted free-swinging
needle on either side of (going through) this bar.

12. Needle Electroscope
Touch ball
Needle
Conductive bar

13. Needle Electroscope
If a charge contacts the touch ball then the bar and
needle will become the same charge as the rod (by
conduction) and will swivel away.
Neutral Charged

14. Needle Electroscope
Copy this example into your notes.
Neutral Charged