Question

An A.C ammeter can be used in
(A) only in DC circuits
(B) only in AC circuit
(C) both in AC and DC circuit
(D) neither in AC nor in DC circuits

Answer 1

Hint: Ammeter is a device which is used to measure current in a given circuit. We have seen such in laboratories and we know that in order to measure current in a circuit we have to connect the ammeter always in series, also, we know about AC and DC. Let us see now.

Complete step by step answer:
Electric current is the rate of flow of charge. If the direction of this electric charge changes regularly, then the resultant current is called Alternating Current (AC). The device that is used to measure the Alternating Current in an electric circuit is called AC ammeter. Now we have to see whether we can use AC ammeters only in AC circuits or both in AC and DC circuits. As the name suggests it is used in AC circuits and only we have to check for DC circuits now.
An AC ammeter works by measuring the effective value of current in the circuit and it shows the value of current that would be needed to produce the heating effect as that produced by that current. For heating it does not matter whether the current is AC or DC. So, the AC ammeter can be used both in DC as well as AC circuits.

Hence, the correct option is (C).

Note:Contrary to this a DC ammeter cannot measure AC because the DC ammeter measure the average value of electric current and we know that the average value of AC over a complete cycle is zero, so when DC ammeter is put to use in a AC circuit, it shows no deflection.