A circular coil of electric current has the same properties as a magnet: if it is allowed to rotate freely about a vertical axis, it points north and south like a magnetic needle; if two such coils ar

A circular coil of electric current has the same properties as a magnet: if it is allowed to rotate freely about a vertical axis, it points north and south like a magnetic needle; if two such coils are close, they will exhibit attraction like a magnetic bar. Or the effect of mutual repulsion. Thinking about this discovery, Ampere proposed the famous molecular current hypothesis. In the process of establishing electrodynamics, Ampere always insisted on applying Newton's full set of methods to electromagnetic research. Newton divided everything into particles with mechanical properties, and Ampere simplified all electric fluids and magnets into a collection of electric current elements with electrodynamic characteristics. Newton established the formula of universal gravitation through mathematical derivation and a large number of inductive observations, and Ampere also After the same steps, the law that electrodynamic force is inversely proportional to the square of distance was discovered; Newton believed that there was no need to consider the cause of force formation, and Ampere's molecular current hypothesis also did not involve the origin of molecular current. Every step Ampere took when creating electrodynamics can reflect Newton's thoughts and style. We can even learn Newton's way of thinking and mathematical methods from Ampere. Ampere went through the process from observation to experiment, from experiment to establishing mathematical model, and then to establishing general formula of electrodynamics. In this long process, he emphasized experiment most. He believes that experiments can help him select the basic factors of phenomena, test mathematical models and simplify derivation steps, and verify the correctness of formulas. He believed that this whole set of methods belonged to Newton. Therefore, Maxwell called Ampere "the Newton of electricity". In his "On Electricity and Magnetism", Maxwell spoke highly of Ampere's work. He wrote: "Ampere's experimental studies, by which he established the laws of mechanical action between electric currents, are one of the most brilliant achievements in science. "The whole theoretical and experimental investigation seems to have sprung from the mind of this 'Newton of Electricity' and was fully equipped, complete in form and complete in accuracy. It is impeccable and summarized into a relationship that will always be the basic formula of electrodynamics, from which all phenomena can be derived. Ampere deserves to be called the founder and founder of electrodynamics."