If the charge on a body is increased by 2 C, the energy stored in it increases by 21%. The original charge on the body in coulomb is

Options

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

Answer

(b)

Explanation

Energy stored in body is ,`E alpha q^(2)`
`E_(1)/E_(2) = (q_(1)/q_(2))^(2)`
`rArr 100/121 = (q/q+2)^(2)`
`rArr 10/11 = q/q+2`
`:. Q = 20C`