Question

Magnetic lines of force
(A) Always intersect
(B) Are always closed
(C) tend to crowd far away from the poles of the magnet
(D) do not pass through the vacuum

Answer 1

Hint:
In order to solve this question, we should know that there are two poles of a magnet known as the north pole and south pole, and monopoles of magnetic source don’t exist so here we will discuss the magnetic lines of force and their properties and then will determine the correct option.



Complete step by step solution:
A bar magnet is a magnetic field source that produces a magnetic field and it has two poles on its ends called the north pole and south pole.
Magnetic field lines are the imaginary path lines or curves along which if a monopole would exist there then due to magnetic force of the magnetic that monopole would move along that particular path and hence these field lines show the direction of magnetic field
Most common properties of magnetic lines of force are:
Magnetic lines of force never intersect each other because if it were so then it will represent two directions at the same point which is impossible.
Magnetic field lines easily pass through the vacuum (as they are transverse in nature hence don't require medium)
Magnetic lines of force are very dense at the poles of the magnet.
They form closed loops emerging from the north pole and entering into the south pole.

So, magnetic field lines of force form closed curves.




Therefore, the correct option is B.




Note:
It should be remembered that magnetic field lines emerge from the north pole and enter into the south pole outside the magnet but inside they emerge from the south pole and enter into the north pole and hence always form closed loops.