Cap in Parallel

Two capacitors: either 22 mF and 10 mF, or 0.47 F and 0.22 F, or similar values. The capacitors are referred to as C1 and C2 for the larger and smaller capacitances, respectively.

Plastic canvas (7-mesh)

a 6V battery

A single-pole double-throw knife or rocker switch

Six alligator-clip wires

Six twist ties or 80 cm extra wire

A string of three Christmas light bulbs

Advance preparation:

Solder 10cm (4") wires onto the terminals of the capacitors and the switch. Apply minimal heat to capacitor terminals (or you will risk ruining the capacitor).
Solder together a string of three light bulbs, if necessary.

Understanding capacitors in parallel

Build the circuit shown.

Fasten the two capacitors (C1 and C2) and the switch onto the plastic mesh using twist ties or extra wire. Electrolytic capacitors are marked with a – sign to indicate the terminal to which the negative of the battery should be connected. They will be ruined if the terminals are reversed.
Twist the ends of the wires together to make connections, and use as few alligator clip wires as possible.

Predict first: when you begin to discharge the two capacitors in parallel, do you think the light bulbs will look brighter, dimmer, or the same as compared to one capacitor?

What was the reason you chose the answer above?

As the capacitors discharge through the light bulbs, what factors might be different in this circuit as compared to the one-capacitor circuit?

What do you think the voltage across both capacitors (together) is after they are fully charged?__________V

What do you think the voltage across all bulbs (together) is just as the capacitors start discharging?________V

First complete the drawings of the charging and discharging circuits below and trace the path of the electrons in each circuit with different colored pencils.

Charging and Discharging Capacitors

Charge the capacitors, and discharge them. How bright were the bulbs as compared to a single capacitor discharging through them?

Was anything else different?

What did you learn about capacitors in parallel as compared to a single capacitor?

What happens when capacitors are connected in parallel?(NL)

Where does the formula for equivalent capacitance for a parallel circuit come from? (NL)

(NL)