How does a PMMC instrument read average value of a dc waveform? Is it true for pure dc or pulsating dc as well? I mean what will the meter show if I fed a full wave rectifier's output to it? Will it show its average vaue 2Vm/π? If yes, I don't understand how. Say the meter is an ammeter. So, the current will be pulsating and hence the torque will also be pulsating. How will the pointer come to rest at the average value on the dial? Is there any specific arrangement inside the meter or am I missing some key physics principle here? Same goes for a moving iron instrument. I know that the torque is proportional to the square of current but the current is alternating;hence the torque should also be pulsating. How does the pointer come to rest at the rms value on the dial? Thanks a lot in advance..