Physics 2013 JAMB Past Questions - Question 43: To convert a galvanometer to a voltmeter,a

Correct Answer

A

Explanation

To convert a galvanometer into a voltmeter a high resistance is connected to it in series, since current ought hot flow into 'a voltmeter.
To convert a galvanometer into a voltmeter, you would need to add a series resistor to the galvanometer. This resistor is known as a shunt resistor. The value of the shunt resistor is determined based on the desired voltage range and the sensitivity of the galvanometer.

The shunt resistor is connected in parallel with the galvanometer, allowing a portion of the current to bypass the galvanometer. This ensures that the current passing through the galvanometer remains within its range, preventing damage to the instrument.

To calculate the value of the shunt resistor, you need to know the full-scale current (Ig) of the galvanometer and the desired full-scale voltage (Vf) range of the voltmeter. The formula to calculate the shunt resistor value (Rs) is:

Rs = (Vf / Ig) - Rg

Where:
Rs = Shunt resistor value
Vf = Full-scale voltage range of the voltmeter
Ig = Full-scale current of the galvanometer
Rg = Internal resistance of the galvanometer

Once you have calculated the value of the shunt resistor, you can connect it in parallel with the galvanometer. This will allow the galvanometer to measure voltage within the desired range, effectively converting it into a voltmeter.