Basic Electrostatics System
ES-9080B
24
®
5.
Double the plate separation to 4 mm and repeat the procedure. What happens to the
potential now? Compare the values to the previous case.
3B.2: Q Measured, C Variable, V Constant
1.
Figure 3.3a above shows the equipment set up. The Basic Variable Capacitor has an initial
plate separation of 6 cm and is connected to the +2000 VDC port on the voltage source. The
Faraday Ice Pail is connected to the electrometer, and the electrometer is grounded to earth
ground (i.e., through the COM port on the electrostatics voltage source).
2.
Momentarily ground a proof plane and then use it to examine the charge density of the
capacitor, using the ice pail to measure the charge. Investigate the charge density at
various points on the plates — both on the inner and the outer surfaces. How does the
charge density vary over the plate?
3.
Choose a point near the center of one capacitor plate and measure charge density in this
area at different plate separations. (Keep in mind whether you are increasing or
decreasing the capacitance by moving the plates.) How does the charge vary with
capacitance?
3B.3 Q Measured, V Variable, C Constant
1.
Figure 3.3b shows the equipment set up, which is identical to the setup for B2. The Variable
Capacitor has an initial plate separation of 6 cm and is connected initially to the +3000 VDC
Figure 3.3a: Demonstration Setup
To AC power adapter
Alligator clip
