The potential energy of a particle in a force field is:
`U = (A)/(r^(2)) - (B)/(r )`,. Where `A` and `B` are positive
constants and `r` is the distance of particle from the centre of the field. For stable equilibrium the distance of the particle is

Options

A. `a/b`
B. `b/a`
C. `(2a)/(b)`
D. `(2b)/(a)`

Answer

C

Explanation

`(dU)/(dr)=0,-(2a)/(r^3)+(b)/(r^2)=0,r=(2a)/(b)`