Question

13
(a) A circular coil of 30 turns and radius 8.0 cm carrying a current
of 6.0 A is suspended vertically in a uniform horizontal magnetic
field of magnitude 1.0 T. The field lines make an angle of 60°​

Answer 1

Answer:

(b) It can be inferred from relation (i) that the magnitude of the applied torque is not dependent on the shape of the coil. It depends on the area of the coil. Hence, the answer would not change if the circular coil in the above case is replaced by a planar coil of some irregular shape that encloses the same area.

Explanation:

Radius of the coil, r = 8.0 cm = 0.08 m

Area of the coil  

Current flowing in the coil, I = 6.0 A

Magnetic field strength, B = 1 T

Angle between the field lines and normal with the coil surface,

θ = 60°

The coil experiences a torque in the magnetic field. Hence, it turns. The counter torque applied to prevent the coil from turning is given by the relation,

T = n IBA sinθ … (i)

= 30 × 6 × 1 × 0.0201 × sin60°

= 3.133 N m

(b)