Question

Why is magnetic strength is less in the middle

Answer 1

The bar magnet has two poles positive and negative/ in middle they cancel each other out , more and more perfectly as their charges meet, the boundary is infinite at the meeting as it decreases infinitesimally and perhaps eternally

Answer 2

it is because the magnetic sides are made up of iron and it is south pole and north pole or + - so they attract but the magnetic power is less in the middle because no one uses it and has less power