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Permanent magnets
Beginner
Hard magnetic materials retain magnetisation.
Made of hard ferromagnetic materials (steel, alnico, neodymium) that retain magnetisation. Neodymium magnets reach 1.4 T.
Fridge magnets, hard drives, motors.
Can be demagnetised by heat or knocks.
In more detail
Permanent magnets retain their magnetism without current, because their domains remain aligned. Rare-earth magnets such as neodymium are the strongest common permanent magnets.
Real-world uses
- Loudspeakers and headphones use permanent magnets.
- Electric motors in electric vehicles use rare-earth magnets.
- Fridge magnets, loudspeakers and electric motors use permanent magnets that keep their magnetisation without a current.
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Frequently asked questions
Do permanent magnets lose strength?
Slowly over decades, and faster if heated above the Curie temperature or struck.
Why are rare-earth magnets special?
They have very high coercivity and energy product.
What makes a permanent magnet permanent?
Its domains stay aligned because the material has high coercivity, so it resists demagnetisation.
Related topics in Magnetism & Induction
Hysteresis · Curie temperature · Electromagnets · Magnetic flux · Faraday's law · Lenz's law