An ammeter has low resistance in the circuit as it measures the strong current.
A galvanometer as such cannot be used as an ammeter because it has appreciable resistance and it can measure only a limited current corresponding to the maximum deflection on its scale.
In practice, an ammeter is made by connecting a low resistance S in parallel with a pivoted type moving coil galvanometer G.S is known as shunt. Its value depends upon the range of the required ammeter.
