Intermediate Topic 315 of 1102 States of Matter & Solutions
Tyndall Effect
Scattering of a light beam by colloidal particles making the beam visible.
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In-depth explanation of Tyndall Effect
The Tyndall effect is the scattering of a beam of light by particles in a colloid, which makes the path of the beam visible when viewed from the side. The effect occurs because colloidal particles are large enough to scatter light, whereas the molecules or ions of a true solution are too small to do so. This gives a simple test to distinguish a colloid from a true solution: a solution shows no visible beam. The effect is used in laboratory tests and in estimating particle sizes. It is also seen in fog, where sunlight makes the light beams through the air visible.
Going deeper: Tyndall Effect
Key ideas: Scattering increases with particle size and shorter wavelength; for particles much smaller than the wavelength it follows Rayleigh scattering, proportional to 1 over wavelength to the fourth power, giving a blue tint to scattered light, like the sky. The test for a colloid: shine a laser through it and view from the side. Used in nephelometry to measure turbidity.
Common mistakes and connections: Students think a true solution scatters as much; it does not, because particles are below roughly 1 nm. Another error is confusing the effect with fluorescence or refraction. The beam path being visible shows scattering, not absorption. Links to colloids, atmospheric optics, sunset colour and dust in sunbeams.
Visualization of Tyndall Effect
The Tyndall effect: a light beam is scattered by colloid particles and becomes visible, while a true solution leaves the beam invisible. The interactive lesson shows this as a live animation or chart.
Worked example and use case
A torch beam becomes clearly visible when shone through mist, but the same beam is not visible passing through a clear salt solution.
Frequently asked questions about Tyndall Effect
What is Tyndall Effect?
Scattering of a light beam by colloidal particles making the beam visible.
Is Tyndall Effect a beginner, intermediate or advanced topic?
Tyndall Effect is a intermediate topic in States of Matter & Solutions. It builds on the vocabulary of beginner topics in this area.
What should I learn before Tyndall Effect?
Study these earlier topics in States of Matter & Solutions first: van't Hoff Factor, Abnormal Molar Mass, Colloids.
What comes after Tyndall Effect?
The next topics in States of Matter & Solutions are Brownian Motion and Emulsions.
Can I practise Tyndall Effect with quizzes?
Yes. The interactive lesson includes a self-check question on Tyndall Effect, and the States of Matter & Solutions quiz draws on every topic in this area.
Where Tyndall Effect fits in States of Matter & Solutions
Tyndall Effect is topic 96 of 109 in States of Matter & Solutions.