Question

Studies have shown that a certain type bacteria that live in swamps have a magnetized chain of magnetite as part of their internal structure. The magnetized chain acts like a compass to help the bacteria align itself with the Earth's magnetic field. It is found that in the Northern Hemisphere this bacteria has internal magnetite chains that are opposite in polarity to those of similar bacteria in the Southern Hemisphere. Why? Explain.

Answer 1

The magnetised chain acts like a compass and has a net magnetic dipole moment M.

Earth acts like a huge magnet and it has its own magnetic field. the direction of earth’s field are opposite in direction at the northern hemisphere and southern hemisphere.

A magnetic material placed in an external magnetic field gets magnetized in the direction of external magnetic field.

Therefore, the polarity of magnetization acquired by the bacteria are opposite when placed in the northern hemisphere and southern hemisphere