Which of the following essential features is possessed by an indicating instrument?

The  correct answer is option 4):(All of the above)

Concept:

The essential features are possessed by an indicating instrument deflecting, controlling and a damping device.

Deflecting device:

• The deflection device produces deflecting torque which causes the moving system to move from its zero position.

Controlling device:

• The controlling device produce the controlling torque (Tc) which opposes the deflecting torque and increases with the deflection of the moving system. When the deflecting torque is removed, it also brings the pointer back to zero.

Damping device:

• This device produces damping torque this torque is necessary to bring the pointer to rest quickly. This damping torque (Td) acts only when the pointer is in motion and consistently opposes the motion