Answer: Galvanometer.
- A Voltmeter
- B Galvanometer
- C Transformer
- D Capacitor
Correct answer: B. Galvanometer
Explanation: A galvanometer is built on the principle that a current-carrying coil placed in a magnetic field experiences a torque proportional to the current, causing it to deflect and indicate the current's magnitude.
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.