Answer: 0.0628 A m 2.
- A 0.0628 A m<sup>2</sup>
- B 0.628 A m<sup>2</sup>
- C 0.0314 A m<sup>2</sup>
- D 0.126 A m<sup>2</sup>
Correct answer: A. 0.0628 A m<sup>2</sup>
Explanation: M = IA = 2 × π × (0.1)<sup>2</sup> = 2 × π × 0.01 = 0.0628 A m<sup>2</sup>.
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.