Ewings molecular theory of magnetism

Next we can talk about an important theory regarding electromagnetism.

If we break a magnet into two parts each parts become a magnet with a north pole at one end and a south pole at the other end. If we break it further, we observe the same behaviour. This will continue even if we break the magnet to its molecular level.

Each molecule of a magnetic substance is an independent magnet irrespective of whether the substance is magnetized or not. These tiny magnets are called molecular magnets.

In an unmagnetised state (fig(a)), the molecular magnets are in different orientation. Therefore the net magnetic effect is zero.In the magnetised state (fig(b)), these molecular magnets are arranged in an order. All the south poles are aligned in one direction, and the noth poles in the other direction. Therefore a strong magnetic field is created.





In general, perfect alignment of all the magnets in the entire magnet is difficult to obtain. When this condition is obtained it is called the point of saturation and magnetizing the magnet further cannot increase the strength of the magnet. These postulates are known as Ewings molecular theory named after the scientist who proposed them.