Question 51: Magnetism and Matter

Question

A bar magnet having a magnetic moment of 2.0 $$	imes$$ 105 JT$$-$$1, is placed along the direction of uniform magnetic field of magnitude B 
 = 14 $$	imes$$ 10$$-$$5 T. The work done in rotating the magnet slowly through 60$$^\circ$$ from the direction of field is :

Accepted Answer

$$U =  - \overrightarrow M \,.\,\overrightarrow B $$
So $${U_f} - {U_i} =  - MB(1 - \cos 	heta )$$
$$ =  - 14J$$
So $$W =  - \Delta U = 14J$$

Answer

14 J

Answer

8.4 J

Answer

4 J

Answer

1.4 J

Magnetism and Matter

A bar magnet having a magnetic moment of 2.0 $\times 105 JT-1, is placed along the direction of uniform magnetic field of magnitude B = 14 \times 10-5 T. The work done in rotating the magnet slowly through 60^\circ$ from the direction of field is :

Choose the correct answer: