• AC adapter, breadboard, wire, wire cutters, and strippers.

• Multimeter.

• Pushbutton, SPST. Quantity: 1.

• Resistors and electrolytic capacitors, assorted.

Use the components to set up the circuit shown below, were C1 is a 1,000 μF capacitor, R1 is a 100K resistor, R2 is a 100Ω resistor, and S1 is the pushbutton

Set your meter to measure volts DC, place the probes around the capacitor, and hold down the pushbutton. You should see the meter counting upward as the voltage accumulates on the capacitor. (This is easier with a meter that doesn’t have autoranging, because you won’t have to wait while the meter figures out which range to apply.) Resistor R1 slows the charging time for the capacitor.

Release the pushbutton, set aside your meter, and discharge the capacitor by touching R2 across it for a second or two. Now substitute a 50K resistor for R1, and repeat the measurement. The meter should count upward almost twice as fast as before.