Capacitors

JEE Main level, single correct, medium

133 of 180

Question 133 of 180

If the charge on a capacitor is increased by 2C2C, the energy stored in it increases by 4444%. The original charge on the capacitor is (in CC)

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Answer: (A) 1010

Energy stored in a capacitor is given by E=Q22CE=\dfrac{{Q}^{2}}{2C}.
Let initial charge be Q0{Q}_{0}.
Then, 1.44(Q022C)=(Q0+2)22C1.44\left(\dfrac{{Q}_{0}^{2}}{2C}\right)=\dfrac{{\left({Q}_{0}+2\right)}^{2}}{2C}
⇒1.2Q0=Q0+2\Rightarrow 1.2{Q}_{0}={Q}_{0}+2
Q0=20.2=10C{Q}_{0}=\dfrac{2}{0.2}=10C

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