Question

A circular loop placed in a plane perpendicular to the plane of paper carries a current when the key is ON. The magnetic field lines point from B to A. The N-pole of the resultant magnet is on the face close to:

• A. $A$
• B. $B$
• C. A if the current is small, and B if the current is large
• D. B if the current is small, and A if the current is large

Answer 1

The correct option is A

$A$

Consider the loop as a bar magnet. The field line from B to A is similar to the field lines inside a bar magnet. Since the magnetic field lines point from B to A, it implies that they enter into B and emerge out of A. Clearly, the face close to A is the N-pole as field lines emerge out of the north pole and enter into south pole.