Q180 / 180 · COMEDK 2022 · Physics
The AC voltage across a resistance can be measured using a
- Correct answerAhot wire voltmeter
- Bmoving coil galvanometer
- Cpotential coil galvanometer
- Dmoving magnet galvanometer
Solution
A hot wire voltmeter operates on the principle of the heating effect of electric current, where the heat produced is proportional to the square of the current, $H = I^2Rt$.
Since the heating effect is independent of the direction of the current, it can measure both alternating current (AC) and direct current (DC).
Moving coil galvanometers, potential coil galvanometers, and moving magnet galvanometers rely on magnetic effects, which average to zero over a complete cycle for alternating currents, making them unsuitable for measuring AC voltage directly.
Answer: hot wire voltmeter
Since the heating effect is independent of the direction of the current, it can measure both alternating current (AC) and direct current (DC).
Moving coil galvanometers, potential coil galvanometers, and moving magnet galvanometers rely on magnetic effects, which average to zero over a complete cycle for alternating currents, making them unsuitable for measuring AC voltage directly.
Answer: hot wire voltmeter
Hence, the correct answer is option: 'A'.