Answer: 0.4 N.
- A 0.2 N
- B 0.8 N
- C 0.4 N
- D 4 N
Correct answer: C. 0.4 N
Explanation: F = BIL sin90 = 0.2 × 4 × 0.5 = 0.4 N.
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.