How to Short a Capacitor

Use a small-value capacitor to minimize risk of electrical shock.

A capacitor is a device that stores electrical energy as a field when voltage is applied across the capacitor's leads. When the voltage source is removed from the capacitor's leads, the capacitor will slowly discharge. If a load, such as a resistor, is placed across a charged capacitor's leads, the capacitor will discharge more quickly than if the capacitor was simply disconnected. A capacitor will discharge extremely quickly if its leads are directly connected to each other; this is known as "short-circuiting", or simply "shorting".

Things You'll Need

• Rubber gloves
• 0.47 microfarad non-polarized capacitor
• Electrical wire
• Insulated electrical pliers
• AA battery
• Digital multimeter

Instructions

1. Put on the rubber gloves.

2. Strip each end of the electrical wire to reveal 1/2 inch of bare wire at each end of the wire.

3. Turn on the multimeter and set the measurement scale to "DC Volts."

4. Twist together one end of the wire with one of the leads from the capacitor. Place the loose end of this wire on the positive battery terminal. Place the other capacitor lead on the negative battery terminal. Allow the capacitor to charge for 5 seconds, then remove the capacitor and the wire from the battery.

5. Attach the black multimeter probe to the capacitor lead that had been connected to the negative battery terminal. Attach the red multimeter probe to the loose end of the electrical wire. Observe the multimeter display for a few seconds; the voltage will slowly drop from 1.5 volts to zero volts. When the voltage drops to zero, disconnect the multimeter probes from the capacitor and from the wire. This slow discharge rate is due to the high resistance electrical path through the multimeter.

6. Reconnect the loose end of the wire to the positive battery terminal. Reconnect the unoccupied capacitor lead to the negative battery terminal. Allow the capacitor to charge for approximately 5 seconds and then remove the capacitor and wire from the battery.

7. Use the electrical pliers to quickly touch the tip of the loose wire end to the unoccupied capacitor lead. When the wire is touched to the capacitor lead, there may be a small spark.

8. Connect the loose end of the wire to the red lead on the multimeter. Connect the black multimeter lead to the capacitor. Check the multimeter display; the capacitor voltage will read zero volts.

Tips & Warnings

• It can be dangerous to short circuit a capacitor. A 1.5-volt AA battery does not produce much current, and a 0.47 microfarad capacitor does not store much charge; therefore the risk of electrical shock for this project is low. Larger voltages or larger-capacity capacitors can pose a shock or fire hazard if the capacitor is shorted, and can cause injury or death.

References

• Occidental College: Electrical Hazards, Fuses, and Safety Switches
• Georgia State University: Energy Stored on a Capacitor