Answer: IA.
- A IA
- B I/A
- C A/I
- D I²A
Correct answer: A. IA
Explanation: The magnetic dipole moment of a current loop is m = IA.
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.