2)    Moving-coil meters

    Critical damping is an important feature of moving-coil meters which are used to measure current and voltage. When the reading changes, it is of little use if the pointer oscillates for a while or takes too long to settle down to the new reading. The new reading must be taken quickly in case it changes again. 

again the model can be used to understand the effects of increasing levels of damping.

the picture shows no damping case b = 0

the picture shows light damping case b = 0.1

the picture shows critically damping case b = 2.0
Thus, a pointer is critically damped to allow it to move to the correct position immediately whenever a current flows through it or a voltage is applied across it.

the picture shows heavy damping case b = 5.0