Physics - Lesson 1.3

Lesson 1.3 - Magnetic Earth
How is Earth like a bar magnet?

 Vocabulary
  • compass
  • magnetic declination
  • Van Allen belts
  • solar wind
  • magnetosphere
  • aurora
Compass
  • A compass can be used for navigation.
  • A compass is a device that has a magnetized needle that can spin freely.
  • The needle in the compass usually points north.
 



 Earth as a Magnet
  • A compass behaves as it does because Earth acts as a giant magnet.
  • Just like a bar magnet, Earth has a magnetic field surrounding it and two magnetic poles.
  

Earth's Magnetic Poles
  • Earth's magnetic poles are not located at the geographic poles.
  • When you use a compass, you have to account for the fact that the geographic and magnetic poles are different.
   

Magnetic Declination
  • The angle between geographic north and the north to which a compass needle points is known as magnetic declination.
  • Magnetic declination changes over time because the magnetic poles are slowly moving.