AIIMS 2019 Physics Torque on a Current Loop MCQ Question
A coil is placed in y-z plane making an angle of 30° with x-axis. The current through coil is I, and number of turns are N. If a magnetic field of strength ‘B’ is applied in positive x-direction, then find the torque experienced by the coil: (Radius of coil is R) (N = 100, I = 1 Å, R = 2m, B = 1/π T)
100 N⁻m
50 N⁻m
200 N⁻m
150 N⁻m
Correct Answer
Detailed Explanation
The torque (τ) experienced by a coil in a magnetic field is given by the formula τ = N * I * A * B * sin(θ), where A is the area of the coil, θ is the angle between the normal to the coil and the magnetic field direction. For a circular coil, A = πR², and since the coil is in the y-z plane making a 30° angle with the x-axis, θ = 30°. Substituting the values (N = 100, I = 1 A, R = 2 m, B = 1/π T) yields τ = 100 * 1 * (π * (2)²) * (1/π) * sin(30°) = 100 * 1 * 4 * (1/2) = 200 N·m, confirming option C as correct.
Options A (100 N·m), B (50 N·m), and D (150 N·m) are incorrect because they do not accurately account for the area of the coil or the sine of the angle in the torque calculation, leading to underestimations of the torque experienced by the coil.
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