Dr Gulshan S. answered • 05/30/20
PhD In Physics and experience of teaching IB Physics and Math High sc
Let us understand the functions of galvanometer , ammeter and Voltmeter
A galvanometer is an Electrical device to detect presence of current in a circuit
An ammeter is used to measure current through a given circuit and is connected in series.
A voltmeter is used for measuring potential difference across two given points of a given circuit.
A galvanometer has neither too high nor too low resistance of its own coil
An ammeter has low resistance , where as a voltmeter is comparatively high resistance device.
In order to convert a galvanometer to an ammeter a low resistance is connected in parallel with the galvanometer and the value of this resistance depends on the range of current for which this ammeter is to be used. This converted galvanometer ( now ammeter ) is connected in series . To convert a galvanometer to voltmeter a high resistance is to be connected in series with the galvanometer and this galvanometer ( now voltmeter ) is always connected in parallel to the device whose potential difference/ voltage / emf is to be measured.
Option D is correct
