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in a coil of copper by moving a magnet near it. The colossal technology of electrical engineering was the result of this fundamental experiment converting mechanical energy into electrical one. At the same time, it formed the foundation of the theory of electrodynamics. The fundamental difference between the Newtonian laws and Electrodynamics is the concept of field of force, i.e. an electric charge produces a condition in space around it so that another charge feels a force. This was a much subtler concept than that of Newtonian 'force' and eliminated the existence of ether. It produced a most profound change in the basic concept of physical reality. It was Einstein who clearly recognised this fact 50 years later, when he declared that no ether existed and the electromagnetic fields were physical entities which could travel through empty space and could not be explained mechanically. Ultimately, it resulted in the realization of the electromagnetic nature of light."
47. Satish K. Gupta, op. cit. p 736-
"Source of Electromagnetic Waves
A stationary electric charge produces a static electric field around it. A steady current implies the uniform flow of electric charges. Since, a steady electric current produces a steady magnetic field around it, it follows that an electric charge in uniform motion produces a steady or stationary electric field. Also, an accelerated charge should produce a magnetic field, which varies with time and depends on space. Since an electromagnetic wave is associated with a magnetic field, which is dependent on time and space, it follows that an accelerated charge is the source of electromagnetic wave. The most common way of possessing accelerated motion is the possess simple harmonic motion. A charge oscillating harmonically with a frequency nu-v produces electric and magnetic fields at that point, which vary sinusoidally with the frequency v and then produce electromagnetic waves of same frequency.
The variations in electric and magnetic fields in an electromagnetic wave are perpendicular to each other and to the direction of propagation of the wave. As said earlier electromagnetic waves do not require any material medium and they can propagate in free space (i.e. in vaccum) with the velocity of light.
48. (a) Ibid., p. 579, 582
"Electromagnetic Induction
As said earlier, in 1820, Oersted discovered the magnetic effect of electric current i.e. when a steady current flows through a
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