Question

Magnetic lines of force inside a bar magnet-
(A) are from north pole to south pole of the magnet
(B) do not exist
(C) depend on the area of cross section of the bar magnet
(D) are from south pole to north pole of the magnet

Answer 1

Hint: A bar magnet is a piece of metal with a north pole and a south pole which produces a magnetic field around it. The magnetic lines of forces represent the magnetic field around a magnetic material. The direction of the field is tangential to the magnetic lines of forces.

Complete answer:
When a single magnetic pole is brought near a magnetic material, the force experienced by it due to the magnetism of the magnetic material is called the magnetic field.
The magnetic field of a magnetic material is represented by magnetic lines of forces. These are curved lines which tell us about the strength and direction of the magnetic field. The number of lines of forces at a point tells us about the strength of the field at that point and the tangent at any point gives us the direction of the field at that point.

When talking about a bar magnet, the magnetic lines of forces originate from the north pole and end into the south pole. As we move away from the magnet, the density of lines of forces decreases as the magnetic field decreases. Inside the bar magnet, the lines move from the south pole to the north pole. The density of lines of forces is maximum inside the magnet.
Since the magnetic lines of forces inside a bar magnet move from south pole to the north pole, the correct option is (D).

So, the correct answer is “Option (D)”.

Note: The magnetic lines of forces are closed. The direction of the magnetic field is tangential to them. The solenoid has magnetic lines of forces identical to a bar magnet. A magnet can never exist with a single pole, it always has both the north pole and the south pole.