What happens to a bar magnet when it is heated?

[amp_mcq option1=”Its polarity reverses” option2=”Its magnetism is increased” option3=”Its magnetism remains unchanged” option4=”Its magnetism is either reduced or lost” correct=”option4″]

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UPSC Geoscientist – 2022

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When a bar magnet is heated, the increased thermal energy causes the atoms within the magnetic material to vibrate more vigorously. This increased vibration disrupts the alignment of magnetic domains, leading to a reduction or complete loss of magnetism.

– There is a specific temperature, called the Curie temperature, above which a ferromagnetic material loses its ferromagnetism and becomes paramagnetic.
– Heating below the Curie temperature can still weaken the magnet’s field, especially if the magnet is not uniformly heated or has structural imperfections.

Heating is one way to demagnetize a magnet. Other methods include hammering or exposing it to a strong alternating magnetic field (as in a degausser). The loss of magnetism is due to the disorganization of the microscopic magnetic moments within the material.

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