Size does matter? Rayleigh scattering question

[DeepSeeded]

Why must the size of the particles be much smaller than the wavelength (of say blue light) in Rayleigh scattering? They type that causes the sky to be blue specificly.

In Short: How does a small electromagnetic wave size up the size of the entire particle before deciding how it will interact with the electric charges within which are all the same?

In Long: The way I understand it, electrical charges in the molecules will move in an electric field causing the scattering (or remitting the light but with more power in the blue). So if you had a huge particle made of say Nitrogen molecules (say a Nitrogen Ice Cube if such a thing exists) which cause blue light to be scattered then you would experience the same effect with a huge particle.

And since all molecules have the same electric charges in them (the electron) shouldn't all meterials cause Rayleigh scattering? That would make everything look blue.

 

[Naty1]

Try Wikipedia:
http://en.wikipedia.org/wiki/Rayleigh_scattering

Rayleigh scattering is based on a mathematical approximation (simplification) where particles are much smaller than the wavelength of the impinging light. If that approximation doesn't hold, scattering still happens...but the math is different ...more complex

See Mie Theory, the general solution to Maxwell's equations:

In contrast to Rayleigh scattering, the Mie solution to the scattering problem is valid for all possible ratios of diameter to wavelength,

Better to think of scattering in general and Rayleigh as a special case...

 

[Entropia]

I can assure you that size does matter in the phenomenon of Rayleigh scattering. This is because the size of the particles plays a crucial role in determining how they interact with light waves, specifically in the case of the blue light that causes the sky to appear blue.

Rayleigh scattering occurs when particles in the atmosphere, such as nitrogen and oxygen molecules, scatter light waves in all directions. This scattering is more prominent for shorter wavelengths, such as blue light, which is why the sky appears blue to our eyes.

Now, to answer the question of why the size of the particles must be much smaller than the wavelength of light, we need to look at the concept of electromagnetic waves. These waves have both electric and magnetic components, and they interact with charged particles in different ways depending on their sizes.

When the size of the particle is much smaller than the wavelength of light, the electric field of the wave can easily interact with all the individual charges within the particle. This interaction causes the particles to scatter the light in all directions, resulting in the blue sky effect.

However, when the particle size is comparable to the wavelength of light or larger, the electric field of the wave cannot interact with all the charges within the particle. As a result, the scattering is not as prominent, and the sky would not appear as blue.

Furthermore, not all materials cause Rayleigh scattering because it depends on the composition and structure of the material. For example, gases like nitrogen and oxygen have symmetrical structures, making them more susceptible to Rayleigh scattering. In contrast, materials like metals have more complex structures that do not interact with light in the same way.

In conclusion, the size of the particles plays a significant role in Rayleigh scattering, and it is essential for the blue light to interact with all the individual charges within the particles to create the blue sky effect. Without this size difference, the scattering would not be as prominent, and the sky would not appear blue.