Two equal point charges are fixed at x = -a and ` x = +a ` on x - axis . Another point charge Q is placed at the origin . The change in electrical pot . Energy of Q , when it is displaced by small distance 'x' along x - axis is approximately to :

Options

A. x
B. `x^(2)`
C. `x^(3)`
D. `1/x`

Answer

B

Explanation

`DeltaU = U_(b) - U_(i) = kQq [ 1/(a+x) +1/(a-x)] - (2kQq)/a ` .