# Tyndall vs Rayleight Light Scattering

• inigo
In summary: Tyndall effect happens with particles that are roughly the size of the wavelength of light, while Rayleigh scattering happens with very small particles (< 1nm) such as O2 and N2 in the atmosphere. The Rayleigh scattering mechanism is when energy from the light wave excites the O2 or N2 electrons to a higher unstable state. When the electron returns to its lower stable state, a photon of the same frequency is released in a random direction. Blue light gets scattered more via the Rayleigh effect because it has more energy to excite the electron to a higher unstable state, but does blue scatter more via the Tyndall effect due to a higher degree of refraction just due to its shorter wavelength?
inigo
I've been trying to get some insight into the light scattering mechanism that occurs in colloidal solutions via the Tyndall effect and was hoping some of the resident experts here could shed some light... on this.
Tyndall scattering occurs with particles that are roughly the size of the wavelength of light while Rayleigh scattering occurs with very small particles (< 1nm) such as O2 and N2 in the atmosphere. The Rayleigh scattering mechanism is when energy from the light wave excites the O2 or N2 electrons to a higher unstable state. When the electron returns to its lower stable state, a photon of the same frequency is released in a random direction. My question is, does this same process also happen with larger particles via Tyndall scattering or is it more like a random refraction where the light wave is simply redirected on a complex path through the particle? Blue light gets scattered more via the Rayleigh effect because it has more energy to excite the electron to a higher unstable state but does blue scatter more via the Tyndall effect due to a higher degree of refraction just due to its shorter wavelength?
Thanks!

Although Tyndall effect is well known, the scattering from particles about as large or larger than the wavelength of light is called Mie scattering, not Tyndall scattering. The transition from Rayleigh to Mie scattering is continuous. The original paper by Mie contains all you ever want to know about it.

Your description of the Rayleigh scattering doesn't sound right to me: The molecules never get excited to an unstable state, at least not in the visible range of the spectrum, which would be a resonant scattering event.

I see that Mie scattering is the more general solution to light scattering. I'm not positive on the root mechanism for Rayleigh/Mie scattering. I got the excited electron state for Rayleigh scattering from this site: http://library.thinkquest.org/27356/p_scattering.htm Could be incorrect as applied to Raleigh scattering. I am looking at the Tyndall effect as it applies to colloidal solutions (gelatin mixed in water) and I am trying to understand the limitations of modeling the Rayleigh effect via measuring the Tyndall effect. It's easy to setup an experiment to measure the Tyndall effect in a colloidal solution vs trying to measure O2 N2 scattering in large volumes of air. Makes me wonder how Lord Rayleigh did it?

Thanks,

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## 1. What is the difference between Tyndall and Rayleigh light scattering?

Tyndall and Rayleigh scattering are both types of light scattering, which is the phenomenon where light is redirected or scattered in various directions when it passes through a medium. The main difference between the two is the size of the particles in the medium that cause the scattering. Tyndall scattering occurs when particles in the medium are larger than the wavelength of the light, while Rayleigh scattering occurs when the particles are smaller than the wavelength of the light.

## 2. What causes Tyndall and Rayleigh light scattering?

Tyndall scattering is caused by the scattering of light by particles in a colloid or suspension, such as dust, smoke, or water droplets. These particles are large enough to scatter light in all directions, making the light appear hazy or milky. Rayleigh scattering, on the other hand, is caused by the scattering of light by molecules in a gas or liquid. The smaller size of these molecules causes the light to scatter in a specific direction, resulting in the blue color of the sky and the red-orange color of sunsets.

## 3. How can Tyndall and Rayleigh scattering be observed in everyday life?

Tyndall scattering can be observed in everyday life in phenomena such as the blue color of the sky, the white color of clouds, and the milky appearance of certain liquids, such as milk and fog. Rayleigh scattering can also be observed in the blue color of the sky and red-orange color of sunsets, as well as in the color of the ocean, which appears blue due to the scattering of light by water molecules.

## 4. How do Tyndall and Rayleigh scattering affect the transmission of light through a medium?

Tyndall and Rayleigh scattering both affect the transmission of light through a medium by causing it to scatter in various directions. This scattering can make the light appear hazy or cause it to change color, as seen in the blue color of the sky and the milky appearance of certain liquids. In some cases, such as in the Earth's atmosphere, scattering can also help to scatter harmful radiation, protecting living organisms from potential damage.

## 5. How do scientists use Tyndall and Rayleigh scattering in their research?

Scientists use Tyndall and Rayleigh scattering in various fields of research, including atmospheric science, environmental science, and materials science. In atmospheric science, the scattering of sunlight by air molecules is used to study air pollution and climate change. In environmental science, the scattering of light by pollutants in water and air can be used to monitor and measure the levels of pollution. In materials science, scattering techniques are used to study the size, shape, and composition of particles in various materials, providing valuable information for the development of new technologies and products.

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