A magnetic dipole is under the influence of two magnetic fields. The angle between the field directions is 60º, and one of the fields has a magnitude of 1.2 × 10⁻² T. If the dipole comes to stable equilibrium at an angle of 15º with this field, what is the magnitude of the other field?

Magnitude of one of the magnetic fields, B₁ = 1.2 x 10^-2 T

Magnitude of the other magnetic field = B₂ 

Angle between the two fields, 0 = 60°

At stable equilibrium, the angle between the dipole and field B₁, 0₁ = 15°

Angle between the dipole and field B₂, 0₂ = 0 – 0₁ = 60° – 15° = 45°

At rotational equilibrium, the torques between both the fields must balance each other.

.-. Torque due to field B₁ = Torque due to field B₂

MB₁ sin0₁ = MB₂ sin0₂

Where,

M = Magnetic moment of the dipole

Therefore ,  B₂ =( B₁ sin0₁ )/sin0₂

= 1.2 x10⁻² x sin 15°/sin 45° = 4.39 x 10^-3 T

Hence, the magnitude of the other magnetic field is 4.39 x 10^-3 T.