A capacitor is made from two parallel plates separated by a distance d, and each has area A. The capacitor holds a charge Q. (a) What is the energy stored in the capacitor? (b) A mechanical force pulls the plates apart, without changing the stored charge, until they are 2d apart. Now how much energy is stored? (c) Explain the difference between (a) and (b).

asked by lindsey

12 years ago

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1 answer

(a)
C=εε₀A/d
Energy=Q²/2C
(b)
C₁=εε₀A/2d=C/2
Energy=Q²/2(C/2)= Q²/C

answered by Elena

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Question

A capacitor is made from two parallel plates separated by a distance d, and each has area A. The capacitor holds a charge Q. (a) What is the energy stored in the capacitor? (b) A mechanical force pulls the plates apart, without changing the stored charge, until they are 2d apart. Now how much energy is stored? (c) Explain the difference between (a) and (b).

1 answer

(a)
C=εε₀A/d
Energy=Q²/2C
(b)
C₁=εε₀A/2d=C/2
Energy=Q²/2(C/2)= Q²/C

Ask a New Question or answer this question.

Elena · Answer

(a) C=εε₀A/d Energy=Q²/2C (b) C₁=εε₀A/2d=C/2 Energy=Q²/2(C/2)= Q²/C