Which device uses an electromagnet to detect small amounts of current?

Which device uses an electromagnet to detect small amounts of current?

• A. Solenoid
• B. Transformer
• C. Electric Motor
• D. Galvonometer

Answer: (D)

The key idea is turning a small electric current into a visible, measurable deflection using a current-carrying coil in a magnetic field. In a galvanometer, the current flows through a coil that becomes an electromagnet. This coil sits in a fixed magnetic field (often from a permanent magnet). The interaction between the coil’s magnetic field and the external field exerts a torque on the coil, causing it to deflect. The deflection is proportional to the current, so even very small currents can produce a detectable movement. The other devices aren’t designed to detect tiny currents: a solenoid mainly creates a magnetic field to actuate motion; a transformer uses magnetic coupling to transfer energy rather than to sense current; an electric motor uses current to generate motion but is not a precise current detector. So the device that uses an electromagnet to detect small amounts of current is the galvanometer.

The key idea is turning a small electric current into a visible, measurable deflection using a current-carrying coil in a magnetic field. In a galvanometer, the current flows through a coil that becomes an electromagnet. This coil sits in a fixed magnetic field (often from a permanent magnet). The interaction between the coil’s magnetic field and the external field exerts a torque on the coil, causing it to deflect. The deflection is proportional to the current, so even very small currents can produce a detectable movement. The other devices aren’t designed to detect tiny currents: a solenoid mainly creates a magnetic field to actuate motion; a transformer uses magnetic coupling to transfer energy rather than to sense current; an electric motor uses current to generate motion but is not a precise current detector. So the device that uses an electromagnet to detect small amounts of current is the galvanometer.