Why do magnets lose strength when hot?
Show answer & explanation
Answer: Heat disrupts atomic alignment
Heat melts magnetic coating — Wrong. Permanent magnets aren't coated—magnetism comes from internal atomic structure. Heat disrupts alignment of magnetic domains.
Electrons move slower when hot — Wrong. Electrons actually move faster when heated. Magnetism weakens because thermal vibrations randomize the aligned magnetic domains.
Heat disrupts atomic alignment ✓ — Correct! Permanent magnets work through aligned magnetic domains—regions where atomic magnetic moments point same direction. Heat increases atomic vibrations, disrupting this alignment. Above Curie temperature (~770°C for iron), thermal energy completely randomizes domains—permanent magnetism lost! Cooling below Curie point doesn't restore magnetism (need re-magnetization). This is why dropping magnets or heating them weakens magnetism. Refrigerator magnets lose strength in hot cars!