A voltmeter consists of a 25Ω coil connected in series with a 575Ω resistor. The coil takes 10 mA for full scale deflection. What maximum potential difference can be measured on this voltmeter?

Concepts/Formula used:

Ohm’s Law:

Potential Difference (V) across a resistor of resistance R when current I passes through it is given by Ohm’s law:

Note that 1A = 100mA.

Note that the current at full deflection is .

The voltmeter can be represented as follows:

It is given that the resistances are in series.

Potential difference is maximum when there is full scale deflection and is given by Ohm’s law:

Thus, maximum potential difference that can be measured is 6V.