# A PMMC type voltmeter, having a full-scale reading of 250 V and an internal resistance of 400 kilo-ohms, is connected with the series resistance of 100 kilo-ohms. Calculate the sensitivity of the voltmeter (in Ohms/Volts).

A PMMC type voltmeter, having a full-scale reading of 250 V and an internal resistance of 400 kilo-ohms, is connected with the series resistance of 100 kilo-ohms. Calculate the sensitivity of the voltmeter (in Ohms/Volts).

### Voltmeter sensitivity (ohm per volt ratings)

The sensitivity of a voltmeter is given in ohms per volt. It is determined by dividing the sum of the resistance of the meter (Rm) plus the series resistance (Rs), by the full-scale reading in volts. In equation form, sensitivity is expressed as follows:

Sensitivity (S) = (Rm + Rs) ⁄ Vfld

Now as per the given question

Rm= 400 KΩ

Rs = 100 KΩ

Vfld= 250 V

S = (400 + 100) ⁄ 250

S = (500 × 103) ⁄ 250

S = 2000 ohm/volt