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Light waves are often depicted as sine waves... Why is it so?

What's actually waving?

And what does the sine wave signify and represent? enter image description here

What does wavelength of light mean/signify? and how is it calculated for specific colors?

Thank you! :)

LuciferP
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  • Thank you! but this doesn't answer all my queries...I'm looking for a simple and detailed answer... – LuciferP Aug 16 '22 at 13:47
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    @LuciferP - 'simple' and 'detailed' contradict each other much of the time. – Jon Custer Aug 16 '22 at 13:50
  • Does this answer some part of your question? - In what medium are non-mechanical waves a disturbance? The aether? – mmesser314 Aug 16 '22 at 14:05
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    The electric and magnetic field change in amplitude with a frequency. The figure you supplied shows the wavelength as the bar measured between two points of constant phase, in this case the peaks of the wave. The ratio of wavelength to frequency is the speed of light. But really numerous YouTube and wikipedia pages and textbooks have whole pages at all levels of sophistication that walk you through this electromagnetic waves. – UVphoton Aug 16 '22 at 14:07
  • Electric and magnetic fields are waving. – Agnius Vasiliauskas Aug 16 '22 at 14:08
  • How is the wavelength for specific colors like red or violet calculated? – LuciferP Aug 16 '22 at 16:09
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    How "color" corresponds to a given wavelength of light is more of a subjective question than an objective one, and a lot of it depends on how the human eye responds to light of various wavelengths. The wavelength for a specific color can't be "calculated" without making some simplifying assumptions about the nature of the light and how the human eye works. There is definitely not a "simple and detailed" answer for that question. – Michael Seifert Aug 16 '22 at 16:40

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Light is an electromagnetic wave. Under certain conditions, Maxwell's equations in a given region admit a solution of the form $\vec{E}=\vec{E}_0\cos(\vec{k}\cdot\vec{x}-\omega t),\,\vec{B}=\vec{B}_0\cos(\vec{k}\cdot\vec{x}-\omega t+\varphi)$.

In the direction of the wavevector $\vec{k}$, this solution propagates with wavenumber $k:=|\vec{k}|$, wavelength $\lambda:=2\pi/k$, frequency $\omega=ck/n$ for refractive index $n$ (in vacuo $n=1$) and phase velocity $v_g:=\omega/k=c/n$.

This isn't the only solution; one can superpose them. An envelope of such waves of various $\omega,\,\vec{k}$ has group velocity $v_p:=\frac{\partial\omega}{\partial k}$ (you can show $v_p=cn=\frac{c^2}{v_g}$).

J.G.
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The picture is very missleading. What is waving is an electric field and a magnetic field, therefor we call it an electromagnetic wave. the different colors have different wavelength, which is the distance of two consecutive maxima of the electric field. but the wavelength is so short, one can not really depict it, it is less than $\frac{1}{100000}mm$ but the kind of wave is just the same as the radio waves .

trula
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