Answer: Maximum torque, since torque is greatest when the plane is parallel to the field.
- A Zero torque, since torque generally vanishes once the plane becomes parallel to the field
- B The same torque, since torque on a current loop does not depend on its orientation
- C Half the initial torque value at this new orientation
- D Maximum torque, since torque is greatest when the plane is parallel to the field
Correct answer: D. Maximum torque, since torque is greatest when the plane is parallel to the field
Explanation: Torque on a current loop is τ = mB sin(θ), where θ is the angle between the loop's normal and B; when the plane is parallel to B, the normal is perpendicular to B (θ=90°), giving maximum torque, opposite to the initial perpendicular-plane case where torque was zero.
The magnetic field around a long straight current-carrying wire forms concentric circles, with direction given by the right-hand rule (point thumb along I, fingers curl in the direction of B).
Concept context
Magnetic force on moving charges and currents, the Biot-Savart law, Ampere's law, and the cyclotron - how electric currents create and respond to magnetic fields.