Question

Explain the basic construction and operation of an analog ammeter that utilizes a galvanometer.

What are some issues to watch out for when using such an ammeter?

Answer 1

At the heart of the analog ammeter is a galvanometer. Galvanometer consists of a coil placed in the magnetic field of a permanent magnet. When current flows through the coil, there is a net torque on the coil since it is in a magnetic field. The pointer attached to the coil also turns and the angle is proportional to the magnitude of the current through the coil. The scale behind the pointer is labelled in units of current.

When we connect ammeter to a circuit to measure the current, the voltage across the ammeter must be very small. Otherwise the overall resistance of the circuit will be more and the current shown by the ammeter is less than the actual value. So the resistance of ammeter must be as small as possible.