The work done against electric in increasing the potential difference of a condenser from 20 V to 40 V is W. The work done in increasing its potential difference from 40 V to 50 V will be

Options

A. 4W
B. `(3W)/(4)`
C. 2W
D. `(W)/(2)`

Answer

B

Explanation

`W= V_(t) - V_(1)= (1)/(2) CV_(f)^(2)- (1)/(2) CV_(1)^(2) = (1)/(2) C (40- 30)`
W=600C
`W_(1)= (1)/(2) C (50^(2)- 40^(2))= (900)/(2)C`
`W_(1)= (900)/(2).(W)/(600)= (3)/(4)W`