Calculate torque acting on a bar magnet of length 20 cm magnetic dipole moment `4 xx 10^(-6) Am^(2)` , which is placed in earth's magnetic field of flux density ` 2 xx 10^(-5) T` , perpendicular to the field .

Explanation

`tau = MB sin theta " " (sin 90^(@) = 1)`
=` 8 xx 10^(-11) Nm`.