A current loop is oriented in three different positions relative to a uniform magnetic field.In position 1 the plane of the loop is perpendicular to the field lines.In position 2 and 3 the plane of the loop is parallel to the field as shown.The torque on the loop is maximum in
A)position 1.
B)position 2.
C)position 3
D)positions 2 and 3.
E)all three positions.

Question

A current loop is oriented in three different positions relative to a uniform magnetic field.In position 1 the plane of the loop is perpendicular to the field lines.In position 2 and 3 the plane of the loop is parallel to the field as shown.The torque on the loop is maximum in 
A)position 1. 
B)position 2. 
C)position 3 
D)positions 2 and 3. 
E)all three positions.

Quizplus · Accepted Answer

The torque on a current loop is given by the formula: τ = NIAB sinθ, where N is the number of turns, I is the current, A is the area of the loop, B is the magnetic field strength, and θ is the angle between the magnetic field and the area vector of the loop.

In position 1, the angle between the area vector and the magnetic field is 90°, so sinθ = 1, and the torque is maximum.

In position 2 and 3, the angle between the area vector and the magnetic field is 0°, so sinθ = 0, and the torque is zero.

Therefore, the torque is maximum only in position 1, and there is no torque in positions 2 and 3. The best choice is D, positions 2 and 3.

A Current Loop Is Oriented in Three Different Positions Relative