Galvanometer constant (*G*) is a measure of the sensitivity of a galvanometer, which is a device used to detect and measure small electric currents. It is defined as the amount of current required to produce a deflection of one scale division on the galvanometer's scale. The galvanometer constant is usually expressed in units of amperes per scale division (A/div).

To find the galvanometer constant, you can use the following steps:

1. Connect the galvanometer in series with a known resistance (*R*) and a battery.

2. Adjust the resistance until the galvanometer deflects by one scale division.

3. Measure the current flowing through the circuit using an ammeter.

4. Calculate the galvanometer constant by dividing the current (in amperes) by the deflection (in scale divisions).

For example, if the ammeter reads 0.001 A and the galvanometer deflects by 10 scale divisions, then the galvanometer constant would be:

$$G = \frac{0.001 A}{10 div} = 1 \times 10^{-4} A/div$$

This means that a current of 1 × 10^-4 A is required to produce a deflection of one scale division on the galvanometer.