Question

why heating destroyed the magnetism in a permanent magnet​

Answer 1

Demagnetize a Magnet by Heating or Hammering

If you heat a magnet past the temperature called the Curie point, the energy will free the magnetic dipoles from their ordered orientation. The long-range order is destroyed and the material will have little to no magnetization.

Answer 2

Answer:

If you heat a magnet past the temperature called the Curie point, the energy will free the magnetic dipoles from their ordered orientation. The long-range order is destroyed and the material will have little to no magnetization