Which scattering occurs when structures are much smaller than the wavelength?

Which scattering occurs when structures are much smaller than the wavelength?

• A. Mie scattering
• B. Rayleigh scattering
• C. Raleigh scattering
• D. Compton scattering

Answer: (B)

When structures are much smaller than the wavelength, light scattering falls into the Rayleigh regime. In this situation the incident wave induces tiny oscillating dipoles in the particles, and these dipoles radiate the scattered light. The key feature is a strong dependence on wavelength: the scattered intensity goes roughly as 1 over the fourth power of the wavelength (and also scales with the particle volume). That means shorter wavelengths scatter much more than longer ones, which helps explain why the sky appears blue on clear days. Mie scattering, by contrast, applies when the particle size is about the same as the wavelength, producing a different angular pattern and a weaker wavelength dependence. Compton scattering is a different quantum process involving high-energy photons off electrons and isn’t governed by the relative size of the scatterers to the wavelength.

When structures are much smaller than the wavelength, light scattering falls into the Rayleigh regime. In this situation the incident wave induces tiny oscillating dipoles in the particles, and these dipoles radiate the scattered light. The key feature is a strong dependence on wavelength: the scattered intensity goes roughly as 1 over the fourth power of the wavelength (and also scales with the particle volume). That means shorter wavelengths scatter much more than longer ones, which helps explain why the sky appears blue on clear days.

Mie scattering, by contrast, applies when the particle size is about the same as the wavelength, producing a different angular pattern and a weaker wavelength dependence. Compton scattering is a different quantum process involving high-energy photons off electrons and isn’t governed by the relative size of the scatterers to the wavelength.