Question

An ac ammeter is used to measure current in a circuit. When a given direct current passes through the circuit, the ac ammeter reads $3A$. When another alternating current passes through the circuit, the ac ammeter reads $4A$. Then find the reading of this ammeter (in A), if dc and ac flow through the circuit simultaneously.

Answer 1

Here, $I=\sqrt{I_{dc}^2+I_{ac}^2}=\sqrt{3^2+4^2}=5A$

Thus ammeter reading is $5A$