Question

two circular coils of current-carrying wire have the same magnetic moment. the first coil has a radius of 0.088m, has 140 turns and carries a current of 4.2a. the second coil has 170 turns and carries a current of 9.5a. what is the radius of the second coil? the second coil experiences a torque of 1.53 in a magnetic field of 1.5 T. What is the orientation of the magnetic field?

Answer 1

Here,

let the radius of the second coil is r

for the same magnetic moment

140 * 4.2 * pi * 0.088^2 = 170 * 9.5 * pi * r^2

solving for r

r = 0.053 m

the radius of the second coil is 0.053 m

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let the angle made by the magnetic field with the coil is theta

for the torque

Torque = magnetic moment * magnetic field * cos(theta)

1.53 = 140 * 4.2 * pi * 0.088^2 * 1.5 * cos(theta)

theta = 85.9 degree

the angle made by the magnetic field with plane of coil is 85.9 degree