An electric dipole is placed at an angle of `30^(@)` with an electric field intensity `2xx10^(5)N//C`. It experiences a torque equal to `4Nm`. The charge on the dipole, if the dipole is length is `2 cm`, is

Options

A. 8 mC
B. 2 mC
C. 5 mC
D. `7 mu C`

Answer

B

Explanation

Here, `theta = 30^(@), E = 2 xx 10^(5) NC^(-1)`
`tau = 4Nm, l = 2cm = 0.02 m, q = ?`
`tau = pE sin theta = (ql) E sin theta`
`:. Q = (tau)/(El sin theta) = (4)/(2 xx 10^(5) xx 0.02 xx (1)/(2))`
`= (4)/(2 xx 10^(3)) = 2 xx 10^(-3)C = 2mC`