An electric dipole consists of two equal and opposite charges each of `1 mu C` separated by 2 cm. When it is placed in uniform electric field of `10^5 NC^(-1)` at an angle `theta` with the electric field, it experiences a torque of `2 xx 10^(-3)` Nm. Find the value of angle `theta`.

Explanation

`q = 1 mu c = 1 xx 10^(-6) C`
`2a = 2 cm = 2 xx 10^(-2)m`
`E = 10^5 NC^(-1)`
`theta` = Angle made by the electric dipole with electric field.
`tau = 2 xx 10^(-3)` Nm
`tau = PE sin theta`
`tau = q (2a) E sin theta`
`[because P = q(2a)]`
`sin theta = (tau)/(q(2a)E)`
`(2 xx 10^(-3))/(1 xx 10^(-6) xx 2 xx 10^(-2) xx 10^5) = 1`
`sin theta = 1`
`sin theta = sin 90^@`
`implies theta = 90^@`