Question

In the figure, single touch method of magnetisation is shown. The end A acquires _______.
            

A) North pole
B) South pole
C) It depends on the amount of orientation of domain present at that end
D) It depends on the strength of the bar magnet used.

Answer 1

Hint: We need to understand the mechanism of single touch magnetisation in order to find how the poles of a bar magnet, its orientation of the bar magnet or the strength of the magnet will affect the formation of magnetism in an iron bar.

Complete answer:
We know that there are several methods by which we can produce a magnet from an iron bar. The most common and reliable technique is by making a solenoid arrangement in which the iron bar is used as the core. In this way the iron core can be magnetised. This method of magnetisation keeps the iron piece as a magnet for a good amount of time.
We use the single touch or double touch method to make an iron bar to be magnetic for a very short interval of time. The single touch mechanism involves rubbing or stroking of a bar magnet with an iron bar as we can see in the figure.

The continuous stroking will align the magnetic dipole domains in the iron bar identical to the pole with which the bar is stroked. i.e., the left end of the iron bar being rubbed with the north pole of a bar magnet results in forming a north pole at the left end.
In the figure, we can understand that the left end of the given iron bar becomes a north pole.
This is the required answer.

The correct answer is option A.

Note:
The double touch method involves rubbing the both ends of the iron bar with a pair of bar magnets with the opposite poles on either side. This can make a stronger magnetised iron bar as compared to the magnet made by the single touch method.