Ammeter:
An electromechanical instrument which is used to calculate the amount of current flowing by an electric circuit is known as an ammeter.
It is modified form of a galvanometer. In order to change galvanometer into an ammeter, a low resistance wire is connected parallel to galvanometer. This low resistance wire is known as shunt that is in presence of shunt, a galvanometer act as an ammeter. Ammeter is always linked in series in a circuit.