College of Liberal Arts & Sciences
5F30.10 - Capacitor - Charge & Discharge
Code Number:
References:
5F30.10
Demo Title:
Capacitor - Charge & Discharge
Condition:
Excellent
Principle:
Charging and Discharging of a Capacitor
Area of Study:
Electricity & Magnetism
Equipment:
Genecon Generator, 1 F Capacitor, 20 VDC Power Supply, 25V 10,000 MFD Capacitor, and a 18 Volt Light Bulb.
Procedure:
Video Credit: Jonathan M. Sullivan-Wood.
Connect the Genecon to the 1 F capacitor and count the number of turns that you make with the Genecon. Let go of the handle and the capacitor will discharge back through the Genecon and make it act like a motor (the handle will turn). Interestingly enough the handle will turn in the same direction that you were turning it when you charged the capacitor.
Capacitor: You crank the generator handle as you charge it and current flows into it. You have to apply a torque to because the current flowing in the generator makes it want to act like a motor in turing in the opposite direction. You release the handle and now the capacitor discharges and current flows in the opposite direction. This causes the handle to turn in the origional direction.
Coil: You crank the generator applying a torque. Again, because the generator acts like a motor it resists your efforts forcing you and to do work. You release the handle, the current keeps flowing in the same direction (Lenz's Law). This results in a torque in the same direction that registered your efforts origionally and the handle changes direction.
Details of why this is can be found in the file.
Connect the 10,000 MFD capacitor to the 20 VDC power supply. Charge to about 20 volts. Disconnect the capacitor and connect it to the 18 volt light bulb. It should take about 30 seconds until the light bulb no longer glows visibly.
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- G. D. Freier and F. J. Anderson, "Ed-8", A Demonstration Handbook for Physics.
- G. D. Freier and F. J. Anderson, "Ed-6", A Demonstration Handbook for Physics.
- Earl R. Feltyberger et al., "Energy Storage and Release", Teaching About D. C. Electric Circuits, p. 3.22.
- Borislaw Bilash II and David Maiullo, "Deliverance", A Demo a Day: A Year of Physics of Demonstrations, p. 265.
- Christopher P. Jargodzki and Franklin Potter, "176. A Real Capacitor", Mad About Physics, p. 68, 210.
- Robert Ehrlich, "L.8. Discharging a Capacitor Through a Light Bulb", Turning the World Inside Out and 174 Other Simple Physics Demonstrations, p. 150 - 151.
- W. Bolton, "15. Storage of Charge", Book 4 - Electricity, Physics Experiments and Projects, 1968, p. 31 - 32.
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