Both physics and chemistry study a phenomenon that helps explain why some particles are visible at certain times. This phenomenon is known as the Tyndall effect. It is a physical phenomenon studied by the Irish scientist John Tyndall in 1869. Since then, these studies have had numerous applications in the fields of physics and chemistry. It examines particles that are invisible to the naked eye. However, because they can reflect or refract light, they become invisible under certain conditions.
In this article we are going to tell you everything you need to know about the Tyndall effect and the importance it has for physics in chemistry.
What is the Tyndall effect
This is a type of physical phenomenon that explains how certain particles, whether dissolved in a solution or within a gas, can become visible because they are able to reflect or refract light. At first glance, these particles appear invisible. However, the fact that they can scatter or absorb light differently depending on the medium they are in allows us to distinguish them. They can be seen if they are suspended in a solution and a bright beam of light passes through them perpendicular to the observer's line of sight.
If the light does not pass through this context they cannot be seen. For example, to understand it more easily we are talking about particles such as specks of dust. When the sun enters through the window with a certain degree of inclination we can see the specks of dust floating suspended in the air. These particles are not visible otherwise. They can only be seen when sunlight enters a room with a certain degree of inclination and a certain intensity.
This is known as the Tyndall effect. Depending on the observer's viewpoint, particles that are normally invisible can be seen. Another example that demonstrates the Tyndall effect is when we use car headlights in fog. The light they cast on the moisture allows us to see the suspended water particles. Otherwise, we would only see the fog itself.
Importance and contributions
Tanto en fÃsica como en quÃmica el efecto Tyndall tiene numerosos aportes para ciertos estudios y una gran importancia. Y es que hay gracias a este efecto podemos explicar por qué el cielo es azul. Sabemos que la luz que procede del sol es de color blanca. Sin embargo, cuando entra la atmósfera terrestre, choca con las moléculas de los diferentes gases que la componen. Recordamos que la atmósfera terrestre está compuesta en su mayorÃa por moléculas de nitrógeno, oxÃgeno y argón en menor proporción. En unas concentraciones mucho más inferiores se encuentran los gases de efecto invernadero entre los que tenemos el dióxido de carbono, el metano y el vapor de agua, entre otros.
When white light from the sun strikes all these suspended particles, it undergoes different refractions. The refraction of the sunlight by oxygen molecules in nitrogen causes it to have different colors. These colors depend on the wavelength and the degree of refraction. The colors that are refracted the most are violet and blue because they have shorter wavelengths. This is what gives the sky its color, and it is very similar to what happens in the Rayleigh effect.
John Tyndall also discovered the greenhouse effect thanks to a simulation of Earth's atmosphere in a laboratory. The initial goal of this experiment was to accurately calculate how much solar energy reached Earth and how much was radiated back into space by the Earth's surface. As we know, not all the solar radiation that reaches our planet stays. Some of it is deflected by clouds before reaching the surface. Another part is absorbed by greenhouse gases. Finally, the Earth's surface deflects some of the incident solar radiation depending on the albedo of each type of soil. Following the experiment Tyndall conducted in 1859, he was able to discover the greenhouse effect.
Variables that affect the Tyndall effect
As mentioned earlier, the Tyndall effect is simply the scattering of light that occurs when a beam of light passes through a colloid. This colloid consists of individual suspended particles that scatter and reflect light, making it visible. The variables that affect the Tyndall effect are the frequency of the light and the density of the particles. The amount of scattering observed depends entirely on the light frequency and the particle density.
As with Rayleigh scattering, blue light tends to scatter more strongly than red light because they have a shorter wavelength. Another way of looking at it is that there is a longer wavelength that is transmitted, while a shorter one is reflected by the scattering. The other variable that affects is the size of the particles. This is what distinguishes a colloid from a true solution. For a mixture to be of the colloid type, the particles that are in suspension must have an approximate size in the range between 1-1000 nanometers in diameter.
Let's see some of the main examples where we can use the Tyndall effect:
- When We turn on the lantern light on a glass of milk we can see the Tyndall effect. It is best to use skim milk or dilute the milk with a little water so that the effect of the colloidal particles in the light beam can be seen.
- Another example is the scattering of blue light and can be seen in the blue color of smoke from motorcycles or two-stroke engines.
- The visible beam of headlights in the fog can make floating water particles visible.
- This effect is used commercial and laboratory settings in order to determine the size of the aerosol particles.
I hope that with this information you can learn more about the Tyndall effect.