Northbound Pin

It knows where it's going.

 

 

 

Category - Electricity & Magnetism

Key Idea - Magnetism

 

Purpose - To observes how an easily magnetized object will respond to the Earth's magnetic field

The compass in this photo verifies the accuracy of the North-pointing pin. 
Nature -  Demonstration
Materials -  Petrie dish or Beaker, Pin, Water, Bar magnet, Tissue
Method - 
  1. Use the bar magnet to magnetize the pin.  Do this swiping the pin with one end of the bar magnet repeatedly, making sure to do this in one direction only.  Keep doing this repetitively for a minute or so.

  1. Use the method described in Pin Float to float the magnetized pin on the water surface.

  2. Notice that the pin takes up a particular orientation. Bring the bar magnet close to the floating pin, being careful not to sink it.

  3. The pin will spin to point one end at your magnet.  Take the bar magnet away and the pin will return to its original position.
Safety - Pin pricks?
Explanation - You have just created a simple compass.  Your swiping of the pin caused some of the iron particles in the pin to line up with each other, creating a temporary magnet. This the responds to the Earth's magnetic field and swings to a North-South orientation as a result.
Notes - Chinese sailors used this very system for navigation a thousand years ago.

With further study you can examine how using different poles of the bar magnet will effect the pin in different ways.