I heard that special relativity could be used to explain the working of electromagnet, but couldn't dig anything out of it. Can somebody give some explanation of the above?
I also heard that it is based on the principle that-electric field in one frame of reference is magnetic field in other.
How is it? (I am still in high school, so I don't know much advanced maths and physics.)
Answer
The laws of the EM (electromagnetic) fields contradict the classical Newtonian mechanics. For example, switching reference frames would change the speed of the EM waves, while Maxwells' Equations (and the experimental evidence) result the speed of the EM waves are constant $c$.
This was one of the reasons of the development of the Special Relativity (SR).
In the CM, there are different laws to describe the interaction of moving things and the electric/magnetic forces (f.e. Faraday's law of induction). In the SR framework, the Lorentz-tranformation transforms electric fields to magnetic and vice versa.
Electric engineers study the theory of the electromagnetic fields in non-relativistic approximation belonging to practical scenarios (EM field around a high-voltage wire, EM field in an electric motor, transformator or electromagnets). But they can do this efficiently only after they learned its SR background.
In the practical electromagnet design, the engineers use the classical EM laws and classical mechanics - and a lot of highly complex technical experience collected since centuries.
Thus, SR explains much better, how an electromagnet works, but the CM version is used in the daily design practice.
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