Give use of galvanometer as a voltmeter.

Explanation

1. Galvanometer can be use to measure voltage across a given section of the circuit.

2. A voltmeter has to be joined in parallel with the component through which the potential difference is to be measure.
3. It must draw a very small current otherwise the voltage measurement will disturb the original setup by an amount which is very large.
4. To ensure this, a large resistance R is connected in series with the galvanometer.
5. This arrangement is schematically depicted in figure. Note that the resistance of the voltmeter is, `R_(G)+R~~R` (R is very large).