Question

explain how magnetic becomes magnetized and demagnetized (150 words)

Answer 1

When a material is placed in an external magnetic field, if domains of the material are aligned in the direction of the magnetic field, then material produces a magnetic field in a direction of magnetic field and material possess a magnetic behaviour

If domains are aligned in the direction opposite to the magnetic field, then they produce magnetic field in the direction opposite to the field, hence net magnetic field is zero, material does not possess magnetic behaviour.