Answer: mB sinθ.
- A mB sinθ
- B mB cosθ
- C always mB
- D m/B
Correct answer: A. mB sinθ
Explanation: τ = m × B = mB sinθ, where θ is the angle between m and B.
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.