A 25 cm long solenoid has radius 2 cm and 500 total number of turns. It carries a current of 15 A. If it is equivalent to a magnet of the same size and magnetization (Magnetic moment / volume), then |M| is.

magnetic moment of solenoid is given as NiA where N is total number of turns and A is current in coil and A is area of coil of solenoid. As the solenoid is equivalent of magnet of same size, their magnetic moment will be equal →m=NiA Magnetization →M= m/V = m/Al = NiA/Al = Ni/l Substituting N=500, i=15A, l=0.25m →M=30,000Am⁻¹ Hence, correct answer is option B.