The Earth is a huge magnet and, as such, it has a north and a south magnetic pole. Invisible magnetic lines of force leave the Earth near the Geographic South Pole and enter near the Geographic North Pole. For this reason, compass needles always point toward the north. This phenomenon makes it possible for us to use the magnetic field for navigation.
What causes the magnetic field around the Earth? The details are not fully known, but most scientists believe that liquid iron in the outer core rises away from the inner core/outer core boundary due to the very high temperature of the solid inner core. The rising liquid iron causes convection currents that carry the iron across magnetic field lines in the core. This produces electric currents in the highly conductive liquid iron. These currents then produce their own magnetism, which reinforces the Earth’s magnetic field. Because of the spin of the Earth and the variable nature of the convection currents, the Earth’s magnetic field is constantly in a state of flux.
Some places on the Earth experience this flux in the magnetic field more than others. In many of these magnetic-rich regions, the crust is thicker and levels of iron are higher than in other locations. These locations where magnetic fields are strong can sometimes draw compasses away from magnetic north. Many people believe that such magnetic anomalies exist in the Bermuda Triangle, a famous region of the Atlantic Ocean extending from the Florida coast to Bermuda and Puerto Rico. A number of ships and planes have disappeared in the Bermuda Triangle, and magnetic anomalies could account for some of them going missing because compasses on board would malfunction and perhaps cause deadly navigation errors. Although there is no real evidence that unusually powerful magnetic anomalies exist in the Bermuda Triangle, it does make for a good story! In this experiment, you will use magnets to create your own Bermuda Triangle Effect by investigating how magnetic fields can cancel one another.
|Magnetic Field Direction||Compass Behaviour|