Output transducers are which converts electrical quantity to non-electrical quantity, known as inverse transducers.

B represents flux density in the air gap, A represents area of moving coil and N represents number of turns in the moving coil.

Input transducers are devices which convert non-electrical quantity to electrical quantity and Inverse transducers are devices which convert electrical quantity to non-electrical quantity.

Torque equation is Tf=BANI0, Where Tf is the torque and N is the number of turns.

For a system feedback loop is provided to ensure high stability, linearity.

Transducers are devices which transfers measurand which will be a non-electrical quantity to electrical quantity. Inverse transducers are the devices operating just opposite to transducers.

Permanent Magnet Moving coil converts input electrical quantity to force or torque in the needle system.

In torque equation of a PMMC device torque and flux density have a direct proportionality.

Piezo electric transducers are devices which are capable of converting electrical quantity to non-electrical quantity, which is an inverse transducer.

Quartz, Barium titanate and Lead zirconate are piezo electrical substances which are known for its ability to act as inverse transducers.