Answer: 1.26 × 10-3 T.
- A 1.26 × 10-4 T
- B 6.28 × 10-4 T
- C 2.51 × 10-3 T
- D 1.26 × 10-3 T
Correct answer: D. 1.26 × 10-3 T
Explanation: B = μ0NI/(2R) = (4π × 10-7 × 50 × 2)/(2 × 0.05) = 4π × 10-4 ≈ 1.26 × 10-3 T.
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.