El-4 The Capacitor
Aim
To demonstrate that the capacitance of a parallel plate capacitor is inversely proportional to d the distance of separation.
Apparatus
- Parallel plate capacitor
- Electroscope
- Portalab projector system
- 9V battery
- Hook up wire
Capacitor Setup.
Description
The plates of the capacitor have been shellaced so that they can be brought into contact without shorting. In this position 9V is applied momentarily to the capacitor. No deflection is noted on the electroscope. On separating the plates the electroscope leaves diverge demonstrating that the voltage has increased and the capacitance decreased satisfying the relations
C=Q/V , C= A/d
It is worthwhile noting that for a modest deflection of the electroscope approximately 1000volts is required.
In addition, a dielectric can be placed between the plates when charged and separated. The voltage on the electroscope should drop slightly. Thus, indicating an increase in capacitance.