Shunt is a low resistance device which is connected parallel to the galvanometer in order to convert a galvanometer into an ammeter.
This low resistance device is also used to protect galvanometer from any damage.
Solenoid:
A solenoid is a type of electromagnet, the purpose of which is to generate a controlled magnetic field through a coil wound into a tightly packed helix.
Choke Coil:
A choke coil is a part used in electrical circuits to allow DC current to flow through while blocking AC current from passing.
Amplifier:
An amplifier is an electronic device that can increase the power of a signal (a time-varying voltage or current).