Question

Shunt resistance of ammeter should be of-
A. High value
B. Low value
C. Of any value
D. None of these

Answer 1

Hint: Shunt resistance is a device which is connected to an ammeter to extend its current calculating capacity by getting connected to a resistor in parallel and decreasing the capacity of the resistance. Thus, shunt resistance should have a value which decreases the resistance of the resistors when connected in parallel.

Complete answer:
An ammeter is an instrument which is used to measure the value of electric current. Electric current is the amount of electrons flowing across a cross section in a particular amount of time. Another instrument which can be used to measure electric current is the galvanometer.
Shunt resistance is called for a resistor having a very low value of resistance. It is made up from a material having very low value of temperature coefficient for resistance.

 It is used in an ammeter whose range is to be extended, which can be obtained when connected in parallel. This is because when a resistor is connected to another resistor of very low value, then the equivalent resistance is lower than the lowest individual resistor, which is a shunt resistor. As there is very low resistance, current can flow smoothly. Thus shunt resistance of an ammeter should be very low value.

Thus option B is the correct answer.

Note: A galvanometer is an extremely sensitive device which cannot hold strong currents; hence it is connected to a shunt resistance in parallel to work like an ammeter to measure large currents through a galvanometer. Also, shunt resistance can also be connected in series to work like a load resistance in the circuit.