When was it proven that light is an electromagnetic wave?

[swampwiz]

I know that Maxwell discovered that a disturbance in the electromagnetic field propagates at the speed of light - which Occam's razor would say that light being such a wave would explain it - but not definitively that that is true (e.g., gravity waves, or at least at that time in history, some other type of undiscovered wave could have caused it, etc.) And it seems that by Maxwell's time, the diffraction properties of light had established its wavelength - but without proving that light has a certain frequency, and that it generates measurable electromagnetic effects at that frequency, it could not be proven that it was such an electromagnetic wave. I would think by now, this has been proven (e.g., in LEDs, etc.), but when was it actually proven so?

 

[russ_watters]

Strictly speaking, nothing is ever completely proven in science, but the association with electromagnetism was discovered by Faraday in 1845. Maxwell's work, pretty much fully describing it, followed. The wiki on light describes that.

 

[PeroK]

I know that Maxwell discovered that a disturbance in the electromagnetic field propagates at the speed of light - which Occam's razor would say that light being such a wave would explain it - but not definitively that that is true (e.g., gravity waves, or at least at that time in history, some other type of undiscovered wave could have caused it, etc.) And it seems that by Maxwell's time, the diffraction properties of light had established its wavelength - but without proving that light has a certain frequency, and that it generates measurable electromagnetic effects at that frequency, it could not be proven that it was such an electromagnetic wave. I would think by now, this has been proven (e.g., in LEDs, etc.), but when was it actually proven so?

Heinrich Hertz experimentally verified some of Maxwell's predictions and "proved that the maestro Maxwell was right".

https://en.wikipedia.org/wiki/Heinrich_Hertz