Moving Coil Instrument

Step 1: Galvanometer and Voltmeter.
A galvanometer is an instrument used to measure small currents, whereas a voltmeter is used to measure potential differences (voltages) across two points in a circuit.

Step 2: Conversion Process.
To convert a galvanometer into a voltmeter, a high-value resistor is connected in series with the galvanometer. The high resistance ensures that only a small current flows through the galvanometer when a potential difference is applied, allowing the voltmeter to measure larger voltages. The value of the series resistor is chosen based on the range of voltages to be measured.

Step 3: Conclusion.
Thus, a galvanometer is converted into a voltmeter by connecting a high-value resistance in series with it.