Conversion of Galvanometer into Voltmeter —
- A galvanometer can be converted into voltmeter of given range by connecting a suitable resistance $R$ in series with the galvanometer, whose value is given by
$R=\frac{V}{I_g}-G$
where $V$ is the voltage to be measured, $I_g$ is the current for full scale deflection of galvanometer and $G$ is the resistance of galvanometer.
- Voltmeter is a high resistance instrument and it is always connected in parallel with the circuit element across which potential difference is to be measured. An ideal voltmeter has infinite resistance.
- In order to increase the range of voltmeter $n$ times the value of resistance to be comnected in series with galvanometer is $R=(n-1) G$.
