Magnetism and electromagnetism

• Where are the forces the strongest on a magnet?

  At the poles
• What happens when you place like poled of a magnet next to each other?

  They repel
• What happens when you place unlike poles on a magnet next to each other?

  They attract
• Which materials are magnetic?

  • iron
  • steel
  • cobalt
  • nickel
• What is the direction of the magnetic field?

  from North to South
• What is a permanent magnet?

  A material that produces its own magnetic field
• What is an induced magnet?

  A material that becomes magnetic when in a magnetic field
• What happens to the field strength of a magnetic field when the distance from the magnet is increased?

  It becomes weaker
• What happens when a current flows through a conducting wire?


  A magnetic field is produced around the wire
• What affects the strength of the magnetic field around a wire?

  Size of current and distance from wire
• What does the shaping of a wire to form a solenoid do to the magnetic field?

  Increases the strength of the magnetic field
• What is an electromagnet?

  A solenoid with an iron core
• How do you change the strength of an electromagnet?

  • increasing the number of coils
  • inserting an iron core
  • increasing the current
• What is the motor effect?

  When a conductor placed in a magnetic field experiences a force
• What causes the motor effect?

  Interaction between magnetic fields (wire and permanent magnet)
• What does Fleming's left hand rule show?

  • direction of force (thumb)
  • magnetic field (first finger)
  • current (middle finger)
• The equation linking force, magnetic flux density, current and length

  force = magnetic flux density x current x length
• What do you call a coil of wire carrying a current in a magnetic field that has a tendency to rotate?

  An electric motor