If the charge on capacitor is increased by 5C, the energy stored in the capacitor is increased by 21%, what will be initial charge on the capacitor ?

Options

A. 10 C
B. 20 C
C. 50 C
D. 40 C

Answer

C

Explanation

Suppose, when charge Q on capacitor on when energy at E,
`U = (1)/(2) (Q^(2))/(C)`
If charge become Q + 5 then energy U. = 1.21 U
`:. U = (1.21U)/(1)`
`:. (1)/(2) ((Q+5)^(2))/(C) = 1.21 xx(1)/(2) (Q^(2))/(C)`
`:. (Q+5)^(2) = 1.21 Q^(2)`
`:. Q +5 =1.1 Q `
`:. 5 =0.1 Q :. = 50 C `