Applications and Care of Magnets

Modern Tech Usage

Magnets are everywhere.

Magnets are essential in daily technology, from audio speakers and electric motors to computer hard drives and hospital MRI scanners.
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Key Points

  1. Convert electrical signals into sound inside speakers and headphones.
  2. Store digital data on computer hard drives and credit card strips.
  3. Power electric motors inside fans, mixers, and electric vehicles.
  4. Used in refrigerator door seals, magnetic latches, and pin holders.

Olympiad Fact

Maglev trains use powerful magnets to float above the tracks without friction, reaching speeds over 600 km/h.

Demagnetization

How magnets lose power.

Magnets lose their magnetic strength if they are heated, hammered, or dropped from heights. These actions jumble the internal alignment of magnetic particles.
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Key Points

  1. Heating a magnet strongly over a flame destroys its magnetism.
  2. Hammering or hitting a magnet repeatedly weakens its pull.
  3. Dropping a magnet on a hard floor jumbles its internal particles.
  4. Improper storage with like poles together causes self-demagnetization.

Olympiad Fact

Heating a magnet above a specific temperature called the 'Curie point' causes it to lose its magnetism permanently.

Storing Magnets: Keepers

Preserving the field.

To keep magnets strong, bar magnets are stored in pairs with unlike poles side-by-side, separated by a wooden piece, with soft iron 'keepers' placed across both ends.
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Key Points

  1. Soft iron keepers form a closed loop to prevent magnetic leakage.
  2. A non-magnetic wooden strip separates the two bar magnets.
  3. Always store bar magnets with opposite poles (N-S) next to each other.
  4. Keep magnets away from phones, computers, and credit cards.

Olympiad Fact

While bar magnets need two keepers, a U-shaped horseshoe magnet needs only a single soft iron keeper across its two poles.

Cow Magnets

Saving livestock.

Farmers and vets give cows a smooth cylindrical magnet to swallow. It rests safely in the cow's stomach to trap sharp iron nails or wire eaten while grazing.
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Key Points

  1. Prevents a dangerous condition in cattle called 'Hardware Disease'.
  2. Traps swallowed nails and barbed wire inside the first stomach.
  3. Stops sharp metal from piercing the stomach wall and vital organs.
  4. A single smooth Alnico or ferrite magnet protects the cow for life.

Olympiad Fact

Untreated hardware disease can cause fatal heart infections in cattle if sharp swallowed wire pierces the stomach wall toward the heart.

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