Given figure shows the north and south poles of a permanent magnet in which an ' n ' turn coil of crosssectional area ' A ' is resting, such that, when a current ' I ' is passed through the coil, the plane of the coil makes an angle ' θ ' with respect to direction of magnetic field ' B '. If the plane of magnetic field and the coil are horizontal and vertical respectively, the torque on the coil will be

Question

Given figure shows the north and south poles of a permanent magnet in which an ' n ' turn coil of crosssectional area ' A ' is resting, such that, when a current ' I ' is passed through the coil, the plane of the coil makes an angle ' θ ' with respect to direction of magnetic field ' B '. If the plane of magnetic field and the coil are horizontal and vertical respectively, the torque on the coil will be (A) n I A B cos θ (B) n I A B sin θ (C) n I A B (D) None of the above since the magnetic field is radial

Tardigrade Admin · Accepted Answer

According to question, torque acting on the coil in magnetic field

B

is given as

τ = n I A B sin θ

When the plane of magnetic field and the coil are horizontal and vertical respectively, then normal of coil makes

9 0^{\circ}

with the direction of magnetic field.

∴ θ = 9 0^{\circ}

∴ τ = n I A B sin 9 0^{\circ} = n I A B

$n I A B cos θ$

$n I A B sin θ$

$n I A B$

None of the above since the magnetic field is radial

nIABcosθ

nIABsinθ

nIAB

None of the above since the magnetic field is radial

According to question, torque acting on the coil in magnetic field B is given as τ=nIABsinθ When the plane of magnetic field and the coil are horizontal and vertical respectively, then normal of coil makes 90∘ with the direction of magnetic field. ∴θ=90∘ ∴τ=nIABsin90∘=nIAB

$n I A B cos θ$

$n I A B sin θ$

$n I A B$