Question

A galvanometer in series with a high resistance is called
(A). An ammeter
(B). A voltmeter
(C). A wattmeter
(D). None of the above

Answer 1

Hint: A galvanometer can be used to construct both an ammeter and a voltmeter. An ammeter requires all the current to pass through it to give correct reading of current while no current should flow through a voltmeter to obtain correct reading of voltage. This behaviour can be achieved using resistances.


Complete answer:
A galvanometer can be used to construct an ammeter or a voltmeter. This can be accomplished using a resistance and attaching it to the galvanometer in such a way that we obtain characteristics of a voltmeter or an ammeter.
An ammeter is a device which is used to measure the amount of current in a circuit. It is needed that all the current flows through the ammeter so that we obtain the correct value of current. We can construct ammeters using a galvanometer by attaching a high resistance in parallel to the galvanometer. The parallel combination ensures that all current flows through the galvanometer while the high resistance doesn’t allow current to pass through itself.

A voltmeter is a device which is used to measure the amount of voltage or potential difference in a circuit. It is needed that no current flows through the voltmeter so that we obtain the correct value of voltage. We can construct voltmeters using a galvanometer by attaching a high resistance in series with the galvanometer. The series combination ensures that no current flows through the galvanometer.

Based on this discussion the correct option is option B.

Note: A galvanometer is an electrical instrument which is used to detect whether current is flowing through a circuit or not. It has a needle which shows deflection when current is flowing through a circuit.