Question

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

CBSE Class X Science LA (5 Marks)

Answer 1

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.

Characteristics of magnetic field lines :
 
(a) 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, are closed curves.
 
(b) At the points where the magnetic field is stronger, field lines are crowded and vice-versa.
 
(c) No two magnetic field lines can intersect each other.

Activity : Take a long wire and pass it though the cardboard as shown in figure. Join the free ends of wire to a battery through a key. Insert the key and pass the current. Sprinkle iron filings on card board and tap gently. You will find several concentric rings which are centered at point where the wire passes through cardboard.

Answer 2

Characteristics of magnetic field lines :

(a) 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, are closed curves.

(b) At the points where the magnetic field is stronger, field lines are crowded and vice-versa.

(c) No two magnetic field lines can intersect each other.