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Code Number: 5C30.20
Demo Title: Spark a Capacitor
Condition: Excellent
Principle: Energy stored in a Capacitor
Area of Study: Electricity & Magnetism
Equipment:
5000 V DC power supply, Oil-filled capacitor (2 mfd 5000 vdc), Large, plastic-handled screwdriver, Large Ball Peen Hammer
Procedure:
Best Setup: Run the + lead from the capacitor to a tap switch and then connect the other terminal of the tap switch to the + terminal of the Frederiksen 0-6000 V. power supply as shown. Then connect the negative terminal of the capacitor to the negative terminal of the power supply. Set the power supply to 5000 V. When you close the tap switch, the meter on the power supply will fall to just above zero but will then climb to 5000 V. as the capacitor charges. Let off of the tap switch and discharge the capacitor with the hammer. Remember that capacitors do not discharge instantaneously, so there will be residual charge left in the capacitor unless you leave the hammer across the terminals for several seconds.
Old Version using the 813 model - 5 KV power supplies. 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 (Make sure you do this before discharging the capacitor) 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.
References:
- 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.