Visualizing Field Lines

Your compass will point the way as you seek to reveal the invisible field lines around a bar magnet in this easy activity.

The magnetic field is the area around the magnet where the magnetic forces act. Actually, magnets are made up of many, many tinier magnets called domains, invisible to the naked eye. Each of these domains has its own north and south pole. Part of what makes magnets magnets is that these domains are all aligned in the same direction. In this activity, you'll be able to see the direction and location of magnetic field lines around a bar magnet.

What you’ll need:

  • A bar magnet
  • One compass, or more if possible

What you'll do:

  1. Place the bar magnet in the middle of a table.
  2. Place a compass at each pole of the magnet.
  3. Place several more compasses around the magnet in any place you choose. Be sure that it is not too far away, or the field will not affect it. See if you can figure out where the magnetic field drops off.
  4. After observing what happens, try moving the compasses to other areas around the magnet.

Did you know?

  • Your bar magnet and refrigerator magnets are known as "permanent" magnets, as opposed to the "temporary" magnets such as electromagnets, which are dependent on electrical current.
  • Permanent magnets are generally made of ferromagnetic material, such as iron, cobalt and nickel.

Think Quick!

Which of the following methods would fail if you were trying to demagnetize a permanent magnet?

  • Submerge it in water
  • Hammer it
  • Rub it against another magnet
  • Heat it

Answer - Submerging your magnet would only succeed in getting it wet! Magnetic fields travel just fine through water. However, if you hammer your magent or rub it against another magnet, you’ll knock the domains out of alignment. If you heat a magnet past what’s called its Curie Point, you’ll get the atoms so jittery that they won’t be able to stay nice and aligned. It’s like giving them a couple of Cokes!

 

 

 


For more information contact Carlos Villa at This email address is being protected from spambots. You need JavaScript enabled to view it. or (850) 644-7191.

Last modified on 28 March 2016
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Magnet Academy is a free resource on magnetism & electricity brought to you by the Center for Integrating Research + Learning at the National High Magnetic Field Laboratory.