What is the reason that moving iron instrument could measure both AC and DC but moving coil instrument can't?

( moving coil can't respond quickly as the AC changes its direction so stays at zero - is the explanation i have listen till now )

i tried to get my doubt clear but couldn't find what i was searching for

  • \$\begingroup\$ Instead of listening to / waiting for answers why not do your own research. Figure out how each model works. Many things become obvious when you understand how things work. \$\endgroup\$ – Bimpelrekkie Mar 24 '19 at 10:56
  • \$\begingroup\$ i did research before posting it here..i have posted one of the place i searched for \$\endgroup\$ – DHRUV JOSHI Mar 24 '19 at 11:05

A moving coil meter uses a magnet and this naturally means that the needle moves clockwise for a positive current and anti-clockwise for negative current. The average effect (due to mechanism inertia) and an applied AC frequency of 50 or 60 Hz usually nothing i.e. zero perceptible movement.

A moving iron meter will attract an iron armature irrespective of the direction of the current hence, it will measure AC and usually will measure RMS AC quantities.


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