Energy Stored in a Capacitor Concept

Demonstrations in Energy Stored in a Capacitor

Five antique Leyden jars of varying sizes with glass bodies, metal foil linings, wooden stoppers, and metal rods topped with spherical terminals
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Leyden Jars

Demonstrates capacitance and energy storage using a Leyden jar charged by a Van de Graaff generator. Students see charge accumulate and then discharge as a dramatic spark, making stored electrical …
Large blue cylindrical capacitor with red bolt terminals on top, connected via red and black leads to a Xantrex DC power supply displaying 20.0V and 0.0A, with a yellow-handled screwdriver on the green table
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Shorting a Capacitor

A 90,000 μF capacitor charged to 25V is shorted with a screwdriver, producing dramatic sparks and temporarily welding the screwdriver to the terminals. Demonstrates that even modest stored energy ( …
Bare circuit board from a disposable camera flash with white cylindrical 100 μF capacitor, small xenon flash tube, copper contact bracket, and Duracell AA battery alongside
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Camera Flash

A salvaged disposable camera flash circuit demonstrates capacitor energy storage and rapid discharge. A 1.5 V AA battery charges a 100 F capacitor to over 300 V, which then discharges …
Xantrex power supply displaying 1.5 V and 1.0 A, connected to a black cylindrical supercapacitor in a test tube clamp on a ring stand, SPDT knife switch on a board with copper terminals, and a brass toy oil rig on a wooden base
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Fifty Farads

A 50-farad supercapacitor charged to 2.5 V stores ~156 J — enough to run a toy oil rig for up to 50 minutes. The rig pumps vigorously at first and …
Three blue Mallory capacitors mounted vertically on a black metal stand with alligator clip connections, wired in series to a BK Precision Model 830A autoranging capacitance meter reading 133.1 µF; red jumper cables in foreground

Series and Parallel Capacitors

Three identical 400 µF capacitors are connected in series and parallel while a capacitance meter displays the total capacitance. Students verify the combination rules quantitatively: parallel capacitances add, series capacitances …