Question

Which actions most likely cause the domains within a material to lose their alignment and become more randomized? Check all that apply.

heating the material
rubbing the material against a magnet
passing electricity around the material
placing the material in a magnetic field of opposite polarity
placing the material near a strong magnet
hitting the material

Answer 1

Correct choices: heating the material; placing the material in a magnetic field of opposite polarity; hitting the material.

Brief reasons:
- Heating (up to the Curie temperature) increases thermal agitation so domain alignment breaks down.
- A strong opposite magnetic field forces domain walls to move and can scramble or reverse domain orientations (demagnetizing when the field is removed or varied).
- Mechanical shock (hitting) disturbs domain alignment and can demagnetize.

Why the others are not generally correct:
- Rubbing against a magnet or placing near a strong magnet tends to align domains (magnetize), not randomize them.
- Passing electricity around the material produces a magnetic field; a steady DC field will magnetize, while an alternating or purposely opposing field can demagnetize — so this one only demagnetizes in the alternating/opposite case.