Question

Alternating current can not be measured by dc ammeter because

• A. ac cannot pass through dc ammeter
• B. Average value of complete cycle is zero
• C. ac is virtual
• D. ac changes its direction

Answer 1

The correct option is B Average value of complete cycle is zero

In dc ammeter, a coil is free to rotate in the magnetic field of a fixed magnet.

If an alternating current is passed through such a coil, the torque will reverse it’s direction each time the current changes direction and the average value of the torque will be zero.