Moving iron instruments are scaled at ______.

Moving Iron Instrument

• MI instruments are used for the measurement of the RMS value of current and voltage.
• These instruments have a non-uniform scale.
• It works on the principle of attraction of a single piece of soft iron into the magnetic field.
• In the MI instrument, when the current is passed through the solenoid, a magnetic field is set up inside the solenoid. Then the iron piece gets magnetized which in turn deflects the pointer. 
• The deflecting torque produced is directly proportional to the square of the current.
• The controlling torque is provided by the spring control.
• The damping torque is provided by air friction damping.