a circular coil of radius 120 mm with 10 turns is placed with its plane parallel to the earth magnetic field . when a current of 0.45 A flows through the coil , a compass needle placed at the centre of the coil is seen to be deflected by an angle of 45 degree to the plane of the coil . the intensity of the earth magnetic field is calculated to be?
first i calculated the magnetic moment = 10*pi*(0.12)^2*0.45 unit
then i can calculate the torque = cross product of magnetic moment with magnetic intensity of earth magnetic field = 0.2035 B unit (where B represents the intensity of earth magnetic field )
how can i take into account the deflection of the needle by 45 degrees and where will torque act ?