A) remains same
B) increases two times
C) decreases two times
D) increases four times
Correct Answer: B
Solution :
Energy of a charged capacitor, \[E=\frac{1}{2}\frac{{{Q}^{2}}}{C}\] \[C=\frac{2\pi {{\varepsilon }_{0}}L}{{{\log }_{e}}\left( \frac{b}{a} \right)}\] \[E=\frac{1}{2}\frac{{{Q}^{2}}}{2\pi {{\varepsilon }_{0}}L}{{\log }_{e}}\left( \frac{b}{a} \right)\] ?.(i) for a cylindrical capacitor. where L = length of the cylinders a and b = radii of two concentric cylinders \[C=\frac{2\pi {{\varepsilon }_{0}}(2L)}{{{\log }_{e}}\left( \frac{b}{a} \right)}\] \[E=\frac{1}{2}\frac{{{(2Q)}^{2}}}{C}\] \[=\frac{1}{2}\frac{{{(2Q)}^{2}}}{2\pi {{\varepsilon }_{0}}(2L)}{{\log }_{e}}\left( \frac{b}{a} \right)\] ?..(ii) From Eqs. (i) and (ii), we get \[E=2E\]
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