P7 specification

• Explain how behaviour of a magnetic compass is related to evidence that core of Earth must be magnetic

  when not near a magnet, compasses always point north because earth generates its own magnetic field, showing core must be magnetic
•  explain the difference between permanent and induced magnets

  • permanent magnets produce their own field
  • induced magnets are magnetic material that turn into a magnet once in a magnetic field
• 1. apply current to rails in a horseshoe magnet
  2. bar on rails to complete circuit
  3. force rolls bar along rail
  4. strength of force increases with magnetic field
  5. force increases with current through conductor