Class 12 Physics Magnetism and Matter Introduction

Introduction

Magnetism is the phenomenon due to which certain substances attract pieces of steel, iron, nickel etc.

Magnets are used in many devices like electric bell, telephone, radio, loud speaker, motors, fans, screw drivers, lifting heavy iron loads, super-fast trains especially in foreign coutries, refrigerators etc.

Magnetite is the world’s first magnet. This is also called natural maget.  Though magnets occur naturally, we can also impart magnetic property on a substance. It would be an artificial magnet in that case.

History of magnets

  • As early as 600 BC in Greece, shepherds observed that their wooden shoes which had iron nails struck at some places on the ground.

  • An island in Greece called magnesia has magnetic ore deposits. The word magnet is derived from here.
  • The technological use of magnet at around 400 BC by Chinese was remarkable. A thin piece of magnet when suspended freely always points towards North-South direction. This fact was utilised by a Chinese emperor Huang-ti to win a war.

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