Attraction and Repulsion

📚 Key Concepts

🔹 Law of Magnetic Attraction and Repulsion

Like poles repel each other, and unlike poles attract each other.

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Magnetic Interactions:

  • N-N: Repel (push away)
  • S-S: Repel (push away)
  • N-S: Attract (pull together)
  • S-N: Attract (pull together)

🔹 Understanding Forces

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Attractive Force:

  • Unlike poles create pulling force
  • Brings magnets closer together
  • Overcomes other forces like friction
  • Stronger when magnets are closer

Repulsive Force:

  • Like poles create pushing force
  • Drives magnets apart
  • Can make objects move without contact
  • Used in magnetic levitation

🔹 Testing for Magnets

How to identify a magnet:

  • Repulsion test: Only magnets show repulsion
  • Attraction test: Both magnets and iron show attraction
  • Compass test: Only magnets deflect compass needle
  • Suspension test: Only magnets align North-South

Difference between Magnet and Iron:

  • Iron bar: Attracts to both poles of magnet
  • Magnet: Shows both attraction and repulsion
  • Key test: Repulsion confirms it’s a magnet

🔹 Magnetic Field Through Materials

Magnetic force can act through non-magnetic materials.

Materials that DON’T block magnetism:

  • Wood, plastic, glass, paper
  • Cardboard, cloth, aluminum
  • Water, air, most non-metals

Materials that CAN block magnetism:

  • Thick iron or steel sheets
  • Magnetic shielding materials
  • Multiple layers of magnetic materials

Practical Applications:

  • Magnetic games and toys
  • Picking up objects through containers
  • MRI machines work through human body