P15 electromagnetism

• permanent magenets

  • their magnetism is there all the time and can't be turned on or off
  • have north and south poles
• magnets are made from magnetic materials that can be magnetised or will be attracted to a magnet
• magnetic materials

  • iron
  • cobalt
  • nickel
• magnets create magnetic fields
• magnetic fields fill the space around a magnet where the magnetic forces work to attract or repel magnetic materials
• magnetic fields can be detected by iron filings which line up in the magnetic field
• magnetic fields

  • are symmetrical
  • go from north to south
  • lines are closer where the fields are stronger
• magnetically hard


  hard to de magnetise and hard to magnetise
• magnetically soft 


  easy to magnetise and easy to de magnetise
• induce magnetism

  • when a magnetic material has been placed in a magnetic field
• temporary magnet

  • alloy with iron cobalt or nickel
  • have weak magnetic fields
• when a wire has a current flowing through it a magnetic field is induced around the wire
• the magnetic field around a solenoid resembles a bar magnet
• the magnetic field of a solenoid can be increased by

  • decrease distance between turns
  • increase current
  • increase amount of turns
  • place a magnet or iron bar inside
• electromagnets can be turned on and off
• electromagnetic devices

  1. the switch is pressed
  2. a current flows through the electromagnet
  3. the electromagnet attracts the armature
  4. the hammer hits the bell
  5. the contact is broken
  6. the whole process repeats
• if a wire with a magnetic field is placed in between two magnets, they will move it
• motor effect

  1. the wire is induced with a magnetic field when the circuit is turned on
  2. the magnetic field of the wire is moved by the magnet
  3. the wire turns halfway
  4. the commutator swaps the direction of current swapping the charge
  5. the wire is moved again and turns halfway back to where it started
  6. these repeat until the circuit is turned off
• when a wire is moved through a magnetic field s potential difference is induced across the ends of the wire