Question

The strength of a magnet field is ____ in the middle and ____ at its end
A) Weakest, weakest
B) Strongest, strongest
C) Weakest, strongest
D) Strongest, weakest

Answer 1

Hint
The magnetic field lines go from North pole to South. All the lines originate from the pole and none are created outside. The polar region is smaller than the rest of the space so the lines have more density near the poles and are weak away from them.

Complete step by step answer
The strength of a magnet is highest at the sides and weakest in the middle. This can be demonstrated by the iron filings experiment.

At the north pole, the magnetic lines of force are emerging out. The ratio of the magnetic lines emerging from there and the area of the magnet at that point is called flux and is a measure of the magnetic field strength at the place. At the poles the area is very less compared to the magnetic lines and hence the strength is highest there. At the middle of the magnet, the area becomes quite large and the magnetic flux or the magnetic field strength decreases.
So, the correct answer is option D.

Note
Imagine you had a bar magnet, and then you placed a bunch of iron fillings around it. The iron fillings will form a certain pattern which will be due to the magnetic lines of force. The density of the iron fillings at a point will give the strength of the magnetic field.