Which device uses a moving coil mechanism to indicate readings in a DC circuit?

Which device uses a moving coil mechanism to indicate readings in a DC circuit?

• A. d'Arsonval
• B. Galvanometer
• C. Voltmeter
• D. Ohmmeter

Answer: (A)

The moving coil mechanism, known as the d'Arsonval movement, converts electrical current into a mechanical deflection. A coil sits in a strong, uniform magnetic field; when current flows through the coil, a torque acts on it proportional to the current. A restoring spring brings it back, so the final deflection of the pointer is proportional to the current, giving a readable DC measurement. This arrangement is ideal for DC because the current direction is steady, producing a consistent, linear response. This mechanism is the defining feature of the d'Arsonval movement, the classic core of a galvanometer and the internal working of many DC meters. While a galvanometer (and meters like voltmeters or ohmmeters built around it) can use this same moving-coil principle, the specific term for the mechanism itself is d'Arsonval, which is why it’s the best choice here.

The moving coil mechanism, known as the d'Arsonval movement, converts electrical current into a mechanical deflection. A coil sits in a strong, uniform magnetic field; when current flows through the coil, a torque acts on it proportional to the current. A restoring spring brings it back, so the final deflection of the pointer is proportional to the current, giving a readable DC measurement. This arrangement is ideal for DC because the current direction is steady, producing a consistent, linear response.

This mechanism is the defining feature of the d'Arsonval movement, the classic core of a galvanometer and the internal working of many DC meters. While a galvanometer (and meters like voltmeters or ohmmeters built around it) can use this same moving-coil principle, the specific term for the mechanism itself is d'Arsonval, which is why it’s the best choice here.