If the charge on a capacitorn is increased by 2C, then the energy stored in it increases by 20 %. The original charge on the capacitor is

Options

A. 10 C
B. 20 C
C. 30 C
D. 40 C

Answer

B

Explanation

`U_(1) =(q_(1)^(2))/(2C ) , U_(2) =(q _(2)^(2)) /(2C ) = 1.21 U_(1)`
` implies q _(2)^(2) = 1.21 q_(1)^(2) implies q^(2) = 1.1 q_(1)`
`implies Delta q= 0.1 q_(1) = 2C implies q_(1) = 20 C `