Question

An electric dipole consists of two opposite charges each 0.05 µC separated by 30 mm. The dipole is placed in an unifom1 external electric field of 10⁶ NC^-1. The maximum torque exerted by the field on the dipole is ______

Options

• 6 x 10^-3 Nm

• 3 x 10^-3 Nm

• 15 x 10^-3 Nm

• 1.5 x 10^-3 Nm

Answer 1

An electric dipole consists of two opposite charges each 0.05 µC separated by 30 mm. The dipole is placed in an unifom1 external electric field of 10⁶ NC^-1. The maximum torque exerted by the field on the dipole is 1.5 x 10^-3 Nm.

Explanation:

`vectau = vecp xx vecE`

∴ `vectau` = pE sinθ

For torque τ to be maximum, θ = 90°

∴ τ = pE sin 90° = pE

= `0.05 xx 10^-6 xx 30 xx 10^-3 xx 10^6` ....[∵ p = q(2l)]

∴ τ = `1.5 xx 10^-3` Nm