The bob of a simple pendulum has mass `2g` and a charge of `5.0muC`. It is at rest in a uniform horizontal electric field of intensity `200V//m`. At equilibrium, the angle that the pendulum makes with the vertical is:
(take `g=10m//s^(2)`)

Options

A. `tan^(-1)(2.0)`
B. `tan^(-1) (0.2)`
C. `tan^(-1)(5.0)`
D. `tan^(-1)(0.5)`

Answer

D

Explanation

If T is the tension in the string then
`T cos theta =mg`
`T sin theta=qE`
Dividing we get
`tan theta = (qE)/(mg)=(5xx10^(-6)xx2000)/(2xx10^(-3)xx10)`=0.5
`rArr theta =tan^(-1)(0.5)`