Lesson 10: What is magnetism

• How do non-contact forces operate?

  Non-contact forces act between objects that are not touching each other.
• How can we tell where the magnetic field is strongest?

  The magnetic field lines are closer together where the field is stronger.
• What are the methods to demagnetise a permanent magnet?

  • Heating it
  • Hitting it with a hammer
  • Placing it in a reversed magnetic field
• What causes non-contact forces?

  Non-contact forces are caused by a field.
• What is a permanent magnet?

  A permanent magnet produces its own magnetic field.
• Which metals become magnetic when placed in a magnetic field?

  The magnetic metals are iron, nickel, and cobalt.
• Why is steel considered a magnetic metal?

  Steel is considered magnetic because it contains iron.
• Are magnetic metals ever repelled by permanent magnets?

  No, magnetic metals are attracted by permanent magnets but never repelled.
• How can iron filings be used to visualize magnetic fields?

  Iron filings can be sprinkled on paper over a bar magnet to show the shape of the magnetic field.
• What happens when two south poles are together?

  Two south poles together will repel each other.
• What type of force is magnetism?

  Magnetism is a non-contact force.
• How can we tell where the magnetic field is strongest?

  The strength is indicated by the closeness of the magnetic field lines.
• Magnetism


  A non-contact force acting at a distance.
• Contact Force


  Force acting when objects touch physically.
• Non-contact Force


  Force acting between non-touching objects.
• Magnetic Field


  Region around a magnet where magnetic forces act.
• Bar Magnet


  Magnet with distinct north and south poles.
• North Pole


  Magnet pole where field lines emerge.
• South Pole


  Magnet pole where field lines converge.
• Magnetic Field Lines


  Visual representation of magnetic field direction.
• Magnetic Field Strength


  Stronger near poles; lines are closer together.
• Permanent Magnet


  Magnet that produces its own magnetic field.
• Magnetic Metals


  Metals that become magnetic: iron, nickel, cobalt.
• Steel


  Magnetic metal due to iron content.
• Demagnetisation


  Process of losing magnetic properties.
• Iron Filings


  Used to visualize magnetic field patterns.
• Magnetic Attraction


  Magnetic metals are attracted, never repelled.
• Like Poles


  Same type poles repel each other.
• Opposite Poles


  North and south poles attract each other.
• Heating


  Method to demagnetize a permanent magnet.
• Hammering


  Physical impact method to demagnetize a magnet.
• Reversed Magnetic Field


  Can demagnetize a permanent magnet.
• Field Line Density


  Closer lines indicate a stronger magnetic field.
• Magnetic Field Visualization


  Iron filings align with magnetic field lines.
• What causes non-contact forces?

  Non-contact forces are caused by a field.
• How do non-contact forces operate?

  Non-contact forces act between objects that are not touching each other.