Question

4.
Calculate torque acting on a bar magnet of length 20 cm, magnetic dipole moment
4 x 10-6 Am2, which is placed in earth's magnetic field of flux density 2 x 10-5 J.
perpendicular to the field.​

Answer 1

Answer:

The torque acting on the bar magnet placed perpendicular to the field is 8*10^⁻¹¹ Nm.

Explanation:

Given data:

Length of a bar magnet (2l)= 20 cm

Magnetic dipole moment (M) = 4*10⁻⁶ Am²

Magnetic field (B) = 2*10⁻⁵T

Magnet is perpendicular to the field so, θ = 90°

To find: torque acting on the bar magnet.

We know,

Torque (τ) = M B sinθ

             = (4*10⁻⁶) * (2*10⁻⁵) * sin90°

                         [∵ sin90° = 1]

               = 8*10^⁻¹¹ Nm