question_answer

To convert a galvanometer into a voltmeter, one should connect a:              [AIPMT 2002]

A)  high resistance in series with galvanometer

B)       low resistance in series with galvanometer

C)       high resistance in parallel with galvanometer

D)       low resistance in parallel with galvanometer

Correct Answer: A

Solution :

Key Idea: A galvanometer has its own resistance low but a voltmeter must have high resistance.

A voltmeter indeed is a modified form of a pivoted coil galvanometer. Since the resistance of coil of galvanometer of its own is low, its resistance is to be increased as is a necessary condition for a voltmeter. For this an appropriate high resistance should be connected in series with the galvanometer as shown.

Note:    The resistance of an ideal voltmeter should be infinite.