In what year was proposed that light is an electromagnetic wave?

  • Thread starter tonyxon22
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I’m not asking about the duality particle/wave behavior. I just want to know when did the notion of light being an electromagnetic wave first came up. Was it before or after Maxwell’s calculations of the speed of waves?
I am currently reading a book that explain the process by which Maxwell calculated the speed of waves, but the book calls that speed “the speed of light” right away. I remained wondering if by the time Maxwell finished his works on explaining the experiments of Faraday through the power of equations, the physicist community was already aware of light being an electromagnetic wave.

If they didn’t know, how much time it has to pass for people to understand that the speed calculated by Maxwell was also the speed of light, since it behaves as an electromagnetic wave.

If they did know that light behaved as an electromagnetic wave, how could they even detect this? If the equations that describe the waves behavior where just freshly made by Maxwell?
 

Answers and Replies

  • #2
davenn
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Hi Tony
from wiki....

Maxwell’s equations for EM fields far from sources[edit]

James Clerk Maxwell first formally postulated electromagnetic waves. These were subsequently confirmed by Heinrich Hertz. Maxwell derived a wave form of the electric and magnetic equations, thus uncovering the wave-like nature of electric and magnetic fields, and their symmetry. Because the speed of EM waves predicted by the wave equation coincided with the measured speed of light, Maxwell concluded that light itself is an EM wave.
and this

Electromagnetic theory as explanation for all types of visible light and all EM radiation

Main article: Electromagnetic radiation

A linearly polarised light wave frozen in time and showing the two oscillating components of light; an electric field and a magnetic field perpendicular to each other and to the direction of motion (a transverse wave).
In 1845, Michael Faraday discovered that the plane of polarisation of linearly polarised light is rotated when the light rays travel along the magnetic field direction in the presence of a transparent dielectric, an effect now known as Faraday rotation.[30] This was the first evidence that light was related to electromagnetism. In 1846 he speculated that light might be some form of disturbance propagating along magnetic field lines.[30] Faraday proposed in 1847 that light was a high-frequency electromagnetic vibration, which could propagate even in the absence of a medium such as the ether.

Faraday's work inspired James Clerk Maxwell to study electromagnetic radiation and light. Maxwell discovered that self-propagating electromagnetic waves would travel through space at a constant speed, which happened to be equal to the previously measured speed of light. From this, Maxwell concluded that light was a form of electromagnetic radiation: he first stated this result in 1862 in On Physical Lines of Force. In 1873, he published A Treatise on Electricity and Magnetism, which contained a full mathematical description of the behaviour of electric and magnetic fields, still known as Maxwell's equations. Soon after, Heinrich Hertz confirmed Maxwell's theory experimentally by generating and detecting radio waves in the laboratory, and demonstrating that these waves behaved exactly like visible light, exhibiting properties such as reflection, refraction, diffraction, and interference. Maxwell's theory and Hertz's experiments led directly to the development of modern radio, radar, television, electromagnetic imaging, and wireless communications.

In the quantum theory, photons are seen as wave packets of the waves described in the classical theory of Maxwell. The quantum theory was needed to explain effects even with visual light that Maxwell's classical theory could not (such as spectral lines

my bolds

cheers
Dave
 
  • #3
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And how was the measure of light speed before the calculation of Maxwell waves speed execute?
 
  • #4
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