The idea of lines of force and the method of their representation belongs to M. Faraday. According to J. Maxwell, this method in the hands of Faraday turned into a “powerful research tool.” Explain the propagation of an electromagnetic field using this method
According to Maxwell’s hypothesis, the once begun process of changing the electromagnetic field in a certain area of space further captures more and more new areas. This is how, in Maxwell’s terminology, disturbances of the electromagnetic field arise. For a qualitative illustration of the propagation of an alternating electromagnetic field, let us turn to experiments with a conductor in which a direct current flows. Around such a conductor there will be a constant magnetic field that does not change in time, that is, the magnetic induction at each point of the field does not change over time. There will be no disturbance of the electromagnetic field in the space surrounding the conductor.
Let’s replace direct current with alternating current. When the current strength in the conductor changes in the surrounding space, the magnetic induction will change. An alternating magnetic field will create a vortex electric field. In turn, the changing electric field will create a magnetic field, etc.
This is how an electromagnetic field appears, which begins to spread in a certain area of space with a certain speed.
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