• Voltmeter sensitivity is defined as reciprocal of the full-scale deflection current.
• The sensitivity of a voltmeter can be defined as the reciprocal of the full-scale deflection current.
• This is because the sensitivity is the ratio of the change in the output of the voltmeter to the corresponding change in the input voltage.
• The output of the voltmeter is directly proportional to the current flowing through it, which is usually the full-scale deflection current. Therefore, the sensitivity can be expressed as the reciprocal of the full-scale deflection current.
• The sensitivity is typically expressed in units of volts per division or millivolts per division on the voltmeter scale.
• A higher sensitivity indicates that the voltmeter can detect smaller changes in voltage, while a lower sensitivity indicates that the voltmeter requires a larger change in voltage to produce a full-scale deflection.

Sensitivity, S = (R_m + R_s) ⁄ V_in