What are magnetic field lines ? List two characteristics of these lines. Describe in brief an activity to study the magnetic field lines due to a current flowing in a circular coil.

Explanation

Magnetic filed lines are representation of the magnetic field path along which an imaginary free north pole would tend to move. The tangent at any point on the magnetic field line gives the direction of the magnetic field at that point.
(i) Emerge at north pole and merge at south pole. Inside the magnet, the direction of field lines is from south pole of magnet to its north pole and are closed curves.
(ii) At the points where the magnetic field is stronger, field lines are crowded and vice-versa.