Alternating current can not be measured by D.C. ammeter. Which of the following best describes the reason for his?
Answer & explanation
Correct answer: option 4
$\text{D.C. ammeter measures average current}$
$\text{For A.C., current changes direction every half cycle}$
$\text{Average over a complete cycle} = 0$
$\Rightarrow \text{No deflection in D.C. ammeter}$
The correct reason is: average value of A.C. over a complete cycle is zero.