Demonstration Manual

Electricity and Magnetism

DEM19 - Charging and Discharging a Capacitor

Objective:

- To illustrate the curve traced by charging and discharging a capacitor through the different values of resistors.

Apparatus:

• Curve trace board
• Oscilloscope (Telequipment D61A)
• 10X probe
• Power supply (6V Lantern battery)

Method:

A 1MFD capacitor is connected in series with a variable high resistance that may be adjusted to values; 1.0, 2.2, 4.7, and 10.0 megohms. Connection is made to a d.c. source through the terminals labelled, "battery 6.0 to 200 volts." The 10X probe from Telequipment D61A is connected to the terminals labelled "oscilloscope." The capacitor will start charging when the switch is closed; and discharge when the switch is opened.

Oscilloscope amplitude and sweep period have been pre-adjusted to give optimum trace display.