Answer: 0.02.
- A 0.2 Ω
- B 0.02 Ω
- C 2 Ω
- D 20 Ω
Correct answer: B. 0.02 Ω
Explanation: S = G I<sub>g</sub>/(I - I<sub>g</sub>) = (20 × 0.005)/(5 - 0.005) = 0.1/4.995 ≈ 0.02 Ω.
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.