Relativity as a bridge between Electricity and Magnetism

The topic of this video is on the deep connection between electricity and magnetism and how Einstein's theory of relativity acts as a bridge connecting these two discrete areas of Physics . One of the crucial triggers for Albert Einstein to work on his Special theory of Relativity was the Maxwell's equations of electromagnetism. The unification of electricity and magnetism as a single theory of electromagnetic theory culminated with Maxwell's equations whose elegance and simplicity attracted Einstein. But it was not just the elegance but the invariance of Maxwell's equations in different inertial frames of reference that spurred Einstein on to thinking about the deep connection between electricity and magnetism. This motivation resulted in Einstein's deep understanding of relativity as a bridge between electricity and magnetism. In fact, Einstein understood that electric and magnetic fields are not separate entities but two aspects of a single electromagnetic field. So, what is measured as an electric field in one inertial frame of reference could be measured as a magnetic field in another inertial frame of reference. Two separate cases are discussed as examples to establish this deep connection between electricity and magnetism and how the electric or the magnetic field is measured in two different frames of reference. Lorentz force on a charged object in an electromagnetic field is introduced and the relativistic connection between electricity and magnetism is established using Lorentz-Fitzgerald length contraction equation. The force between two conductors carrying current is discussed as the second case,which is a fundamental problem in electricity and magnetism in the definition of current and electric charge from thereof, to establish the relativistic connection between electricity and magnetism. This video forms part of a series of lecture videos on the topic of Special theory of Relativity.