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Physics unit 4 capacitors

A mystery capacitor can store 3.0J of energy when connected to a 10V supply. How much energy can it store when connected to a 5.0V supply?

not sure how I can prove this algebraically, can anyone help?
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AndyOC
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Original post by AndyOC
A mystery capacitor can store 3.0J of energy when connected to a 10V supply. How much energy can it store when connected to a 5.0V supply?

not sure how I can prove this algebraically, can anyone help?


First you need to find the capacitance of the capacitor, using E=1/2CV2, and use it to work the energy when connected to a 10V supply. But because the capacitance of the capacitor is constant then in in both case you must get the same value for the capacitor, i.e C=2E1/(V1)2=2E2/(V2)2.

Therefore you could use the shortcut E1/(V1)2=E2/(V2)2.

Edit: the final equation edited
(edited 8 years ago)

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