History of Magnetism

Magnetism is the force exerted by the electrons (negatively charged ions) of a magnet. It is the force where objects like iron attract or repel each other. It can also be defined as the force between electric currents, which attract when they are parallel to each other and repel when they are in opposite directions. The word magnetism is derived from a region called Magnesia in Asia Minor, where a naturally magnetic iron ore lodestone was found.

Each magnet has two poles: north-seeking pole and south-seeking pole. The magnetic strength is maximum at these poles. If a magnet is freely suspended, it automatically aligns itself in the north-south direction. The two like poles of the magnets repel each other and the unlike poles attract each other. Other than iron, there are many other materials like nickel and cobalt that get magnetized when placed in a magnetic field.

History of Magnetism

Magnetism was first discovered in a form of the mineral magnetite called lodestone, which comprised of iron oxide (a chemical compound of iron and oxygen). The ancient Greeks were the first to use lodestone and called it magnet, due to its property to attract iron and materials of same type. Englishman William Gilbert was the first to research systematically on the phenomenon of magnetism by using scientific methods. He also revealed that the Earth is a weak magnet. The early theoretical investigations on the Earth's magnetism were performed by the German Carl Friedrich Gauss.

During the eighteenth century, the quantitative studies of magnetism phenomenon was started by Frenchman Charles Coulomb. He developed the inverse square law of force, which states that 'the force of attraction between two magnetized objects is directly proportionate to the product of their individual fields and inversely proportionate to the square of the distance between them'.

Hans Christian Oersted, a Danish physicist was the first to suggest a relation between electricity and magnetism. Many experiments focusing on the effects of magnetic and electric fields on each other were performed by Andre Marie Ampere and Michael Faraday. But in the nineteenth century, James Clerk Maxwell provided the theoretical foundation to the physics of electromagnetism, proving that magnetism and electricity represent different aspects of the same fundamental force field. In the late 1960s, Steven Weinberg and Abdus Salam conducted theoretical synthesis of the fundamental forces by proving that the electromagnetism is a part of the electroweak force.

The modern understanding of magnetism in condensed matter originated from the work of two Frenchmen: Pierre Curie and Pierre Weiss. Curie analyzed the effect of temperature on different magnetic materials and noticed that the magnetism disappeared suddenly beyond a certain critical temperature (curie point) in materials like iron. Weiss suggested a theory of magnetism which was based on an internal molecular field proportional to the average magnetization, that immediately align the electronic micro magnets in a magnetic matter. The present day magnetism phenomenon which depends on the theory of the motion and interactions of electrons in atoms came from the work and theoretical models of two Germans: Ernest Ising and Werner Heisenberg.

Until 1821, only one kind of magnetism was known which was generated by iron magnets. But today, magnetism, its characteristics and applications are well-known in the field of science and technology. New concepts like study of magnetism in organic matter, diamagnetism, etc, continue to be the areas of interest to many physicists and scientists. The most common and simplest form that we see is the use of magnetism in the magnetic compass.