Question

A bar magnet is at right angles to a uniform magnetic field .The couple acting on the magnet is to be one fourth by rotating it from the position .Tha angle of rotation

Answer 1

angle of rotation is 14.48 degree

Answer 2

We know, torque of a couple in a magnetic field B be,

τ= MBsin θ, where M= magnetic moment

τ is directly proportional to sinθ

So τ₁/τ₂ = sinθ₁/sinθ₂

    τ/(τ/4)= sin90°/sinθ₂

sinθ₂= 1/4

θ₂= 14.5