Physics Demonstrations at Cal Poly Pomona
Demo Index:
Pira Index:
Title:
Description:
This demo shows how parallel plates hold a charge.
Equipment:
1. Braun electroscope
2. Pasco slide capacitor on orange base
3. 10” x 12” glass sheet
4. Zerostat
5. 2 B-A lead
Make sure the leads do not hang close
to the electroscopes or the capacitor.
Procedure:
1. Connect apparatus as shown and place the glass sheet between the capacitor plates.
2. Hold the zerostat near the electroscope's center. Slowly pull the trigger to spray charge onto the electroscope. Move the zerostat away before releasing its trigger. The electroscope indicator should rise slightly (you may have to tap the the electroscope case).
3. Pull the glass up and out from between the plates. The indicator should rise as charge leaves the capacitor and flows onto the electroscope. Slide the plates apart (reducing capacitance further) & the indicator will rise higher.
4. Replace the glass & slide the plates together.
