Answer: galvanometer.
- A galvanometer
- B voltmeter
- C ammeter
- D dry battery
Correct answer: A. galvanometer
Explanation: A galvanometer detects and measures very small currents.
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.