El-6 Biot's Apparatus
Published: Tuesday 14 March 2006 - Updated: Thursday 31 March 2011
To demonstrate that the charge resides on the surface of a statically charged conductor.
- Biot's Apparatus
- Proof plane
- Faraday cylinder
Click on pictures to enlarge.
A spherical conductor A mounted on an insulating stand is charged by contact in the normal way. Two uncharged hemispherical metal caps B which just fit over A are placed in position and then removed.
Tests with the proof plane show that the charge resides only on the outside of the metal caps B.
This experiment demonstrates that the charge on a proof plane can be transferred to an electroscope by having the proof plane touch the inside of the cylinder connected to an electroscope.