5C30.20 - Spark a Capacitor

Code Number:
Demo Title:
Spark a Capacitor
Energy stored in a Capacitor
Area of Study:
Electricity & Magnetism
5000 V DC power supply, Oil-filled capacitor (2 mfd 5000 vdc), Large, plastic-handled screwdriver, Large Ball Peen Hammer

Connect the capacitor to the 5 KV power supply as shown. Turn on the power supply and push up the slide switch slowly so that the capacitor charges at a constant rate as shown on the meter on the power supply. When it reaches about 4500 volts, pull the slide switch down and shut off the power supply before discharging, so as not to damage the power supply. With the hammer or the screw driver discharge the capacitor.

The camera flash units are also a version of energy stored in a capacitor.  It will take up to 10 seconds for the capacitor to charge once the unit has been turned on.  

  • John Carlson, "The Kodak One-Time-Use Flash Camera", TPT, Vol. 42, #6, Sept. 2004, p. 375.
  • Ed-6, 8:  Freier and Anderson,  A Demonstration Handbook for Physics.
  • E-210:  "Sphere Gap Plus Capacitor",  DICK and RAE Physics Demo Notebook.
  • Borislaw Bilash II, “Deliverance“, A Demo A Day – A Year of Physical Science Demonstrations, p. 277.

Disclaimer: These demonstrations are provided only for illustrative use by persons affiliated with The University of Iowa and only under the direction of a trained instructor or physicist.  The University of Iowa is not responsible for demonstrations performed by those using their own equipment or who choose to use this reference material for their own purpose.  The demonstrations included here are within the public domain and can be found in materials contained in libraries, bookstores, and through electronic sources.  Performing all or any portion of any of these demonstrations, with or without revisions not depicted here entails inherent risks.  These risks include, without limitation, bodily injury (and possibly death), including risks to health that may be temporary or permanent and that may exacerbate a pre-existing medical condition; and property loss or damage.  Anyone performing any part of these demonstrations, even with revisions, knowingly and voluntarily assumes all risks associated with them.