5C30.20 • Energy Stored in a Capacitor: Short a Capacitor

Photo Shows the Apparatus Used by the University of Texas at Austin.

Instructions / Notes:

• The short a capacitor demo uses a 400 microFarad capacitor - and - a 350 volt power supply that requires turning on multiple switches.
• To short the two terminals of the 400 microFarad capacitor, the demo office uses a fine # 30 gauge copper wire, which provides a pop sound to the demo.

Performing this Demonstration:

• To begin using this demo, turn-on the main power switch.
• Many faculty make two mistakes when preforming this demo.
• The first error is they fail to turn-on a bank of four switches on the rear of the power supply.
• This bank of secondary switches allow you to ramp up the voltage to 350 volts, without an excess of current at start up.

Photo # 2 shows the bank of secondary switches at the rear of the power supply.

• The second error sone faculty will make is to fail to remove the black wire prior to turning-off the main power switch.
• Disconnect the black wire by pulling gently.
• Turn-off the power supply via the main switch at the front.
• The Shield should by around the capacitor at all times.
• Short the capacitor by pushing down on the small copper wire, with the provided discharge rod.
• The wire will explode.

Photo # 3 shows the small copper wire.

Demo Staff::

• When installing the small copper wire - be sure to clean both ends of the wire with sand paper.
• One sanded end of the small copper wire should be wrapped around the negative post of the capacitor.
• Also, be sure to attach the alligator clip for the black wire to the negative post.

Last updated on August 30, 2017