Question

A DC ammeter and a hot wire ammeter are connected to a circuit in series. When a direct current is passed through a circuit, the DC ammeter shows $6A$. When AC current flows through a circuit, the AC ammeter shows $8A$. What will be reading of each ammeter if DC and AC currents flow simultaneously through the circuit?

• A. $DC=6A,AC=10A$
• B. $DC=3A,AC=5A$
• C. $DC=5A,AC=8A$
• D. $DC=2A,AC=3A$

Answer 1

Answer: (A)

$DC=6A,AC=10A$

Given,

$DCcurrent=6A$

$ACcurrent=8A$

So,

When they are passing simultaneously

Reading of $DCammeter=6A$,

Reading of $ACAmmeter$,

$I^{2}Rt=I_{DC}^{2}Rt+I_{AC}^{2}Rt$ [Heat produced]

$I^{2}Rt=6^2.Rt+8^2.Rt$

$I^2=6^2+8^2=100$

$I=10A$.