Question

A bar magnet has no markings to indicate its poles. How would you find our near which end is its north pole located?

Answer 1

Hint: We will take the help of concepts related to the magnetic field and relate it with magnetic fields and geographic fields of Earth. We will hang the magnet with thread and after this by the use of a compass or another magnet we will get its north pole.

Complete answer:
Magnetic field: We can say that a magnetic field is an area around an object in which the other object can experience a field present in that area. It is basically the field present around a magnet. It can also be created by inducing current in the circuit. Moreover, the field can be created by moving a charge which implies force on another charge which is also moving.
Poles: We know two poles namely North Pole and South Pole. These are taken in relevance with the Earth’s poles. The northern pole of the Earth is called the South Pole of a magnet as well. Similarly, the Southern pole of Earth is basically taken as the North pole of Earth only. This is because of the fact of opposite poles attraction.

 

We can see in the diagram that we have suspended a magnet with a thread. After sometime we will see a change in the direction in poles which resembles the real north and South poles of Earth. But since, as we do not know the poles right now as there are no markings on it, we will try to figure this out with the help of a compass or with the help of a new magnet near it. The positions of poles with magnets can be seen with the new magnet which has itself been marked. This situation is drawn below.

Clearly, if any of the ends repels the North Pole of the marked magnet then, we will get to know the positions of poles of the unmarked magnet. Similarly, we will know its south pole.
We can also know correct naming of poles of magnet by the help of compass which is shown below.

Note:
Consider following points for more knowledge related to the question.
(1) Our Earth has its own magnetic field around it along with North and South poles to which we are familiar.
(2) We can also rub a needle and keep it on a leaf which is further kept on the water's surface. So, the needle side which is charged will get aligned to the line of magnetic field of the Earth.
(3) The magnetic field should be tied freely by thread, so that no hindrance can disturb it.
(4) If in case we were given a circular magnet then we will use the same methods as above but by keeping the magnet standing as the circle faces us. This is because the faces of circular magnets have north and south poles.