Permanent magnet moving coil is use to measure direct current and direct voltage.
It works on the principle of when a current carrying conductor is placed in the magnetic field it experiences a force and then generated deflecting torque which is proportional to the current flowing in the conductor.
An aluminum frame is set over the soft-iron core in which a rectangular coil of wire is wound around the aluminum frame is placed between the permanent magnet.
Due to presence of the magnetic field, the rectangular coil of conductor experiences a force and magnitude of the force is directly proportional to the current flowing in the coil.
An spring which is made up of phosphorous bronze is provide damping torque (Damping torque is the resistive force that opposes angular motion, it is use to reduce the oscillation in the pointer needle).
A pointer shows the deflection which is directly proportional to the flow of current in the conductor.
