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Question

Physics Question on electrostatic potential and capacitance

In a charged capacitor the energy is stored in

A

the edges of the capacitor plates

B

the electric field between the plates

C

both in positive and negative charges

D

positive charges

Answer

the electric field between the plates

Explanation

Solution

We know energy per unit volume stored in electric field =12ε0E2=\frac{1}{2} \varepsilon_{0} E ^{2}
in parallel plate capacitor E=6εE =\frac{6}{\varepsilon}
Energy density =12ε062ε02=\frac{1}{2} \varepsilon_{0} \frac{6^{2}}{\varepsilon_{0}^{2}}
Energy =12ε01ε0(QA)2⋅(A⋅d)→=\frac{1}{2} \varepsilon_{0} \frac{1}{\varepsilon_{0}}\left(\frac{Q}{A}\right)^{2} \cdot(A \cdot d) \rightarrow volume
E=121ε0Q2dAE =\frac{1}{2} \frac{1}{\varepsilon_{0}} \frac{ Q ^{2} d }{ A }
We know C=ε0AdC =\frac{\varepsilon_{0} A }{d}
E=12Q2C(Q=CV)E =\frac{1}{2} \frac{ Q ^{2}}{ C }( Q = CV )
E=12CV2E =\frac{1}{2} CV ^{2}