Question

A circular coil having N turns and radius r carries a current I. It is held in the XZ plane in a magnetic field `Bhati`. The torque on the coil due to the magnetic field is ______.

Options

• `(Br^2I)/(piN)`

• Bπr²I N

• `(Bpir^2I)/N`

• Zero

Answer 1

A circular coil having N turns and radius r carries a current I. It is held in the XZ plane in a magnetic field `Bhati`. The torque on the coil due to the magnetic field is Bπr²I N.

Explanation:

Given: A coil has N turns, r is its radius, I is the current that flows through it, and `Bhati` is the magnetic field that surrounds it. The coil is situated in the XZ plane.

To find: τ, the coil's torque under action. The coil's torque is as follows:

τ = m × B (The coil's magnetic moment is m = NIA).

τ = NIAB sin90 = NIAB = NIπr²B

(A = πr² is the coil's cross-sectional area.)