Magnetic fields are produced by moving electrical charges and by magnetic materials. Earth has a weak magnetic field that causes compasses to point to the north. In the Magnetic Induction Gizmo, students use compasses to map the magnetic field produced by the current in a wire. They can also use a magnetic sensor to measure the strength of that field and compare it to the strength of Earth’s magnetic field.
Many organisms are able to detect Earth’s magnetic field and use Earth’s magnetic field to find direction. For example, migratory birds have been demonstrated to use Earth’s magnetic field to find direction while flying over the ocean or in areas with few natural landmarks. This “sixth sense” is called magnetoreception. New research suggests that these biological compasses exist in non-migratory birds as well. While humans have not been shown to be capable of magnetoreception, we do possess the protein in our eyes that is linked to magnetoreception in other animals.