If damping torque is not provided in an instrument
Right Answer is:
An instrument will show full wave of quantity even under small values
If damping torque is not provided in an instrument the pointer will oscillate about its final deflected position for quite sometime before coming to rest.
Damping Torque: At the final deflected position, when the deflecting and controlling torques are equal, the pointer starts oscillating owing to its inertia and therefore, cannot immediately settle at its final deflected position. If no extra force is provided to damp these oscillations, the moving system will take considerable time before coming to settle to the final deflected position. This is especially undesirable if the number of readings to be taken is quite large.
Air friction, Eddy current damping, Hydraulic damping is used in damping torque.