Inductors - Technical MCQs

Q1:

Current will cause a magnetic field in a conductor as follows:

A An ac current causes a fixed polarity magnetic field.

B A dc current causes a fixed polarity magnetic field.

C A dc current causes an alternating magnetic field.

D An ac current causes a fixed polarity magnetic field and a dc current causes an alternating magnetic field.

ANS:B - A dc current causes a fixed polarity magnetic field.

The difference between the fields produced by an AC or a DC is that the magnetic fields produced by an alternating current is a changing magnetic field (Its direction and magnitude changes with time), while for a DC the field is constant both in magnitude and direction.