Tyndall effect
The Tyndall effect is the scattering of light by colloidal particles, making the path of a light beam visible.
In one line: Tiny particles scatter, so the beam shows itself.
Practice This ConceptUnderstand it
When a beam of light passes through a medium containing very fine suspended particles, those particles scatter the light sideways. This makes the beam's path visible. The effect is seen in fog, smoke, and dusty rooms because the particles are large enough to scatter light but still remain suspended.
Example
Formula and rule
Tyndall effect is a scattering phenomenon caused by fine particles in a medium.
See it worked out
Follow the example line by line, then use the same method on new questions.
Worked example
When sunlight enters a room through a small window in a dusty atmosphere, the path of the beam becomes visible because dust particles scatter the light in many directions.
Method you can reuse
- 1Identify fine suspended particles in the medium.
- 2State that they scatter the light.
- 3Explain that the beam path becomes visible.
- 4Give an example such as fog, smoke, or dust.
- 5Name the effect as Tyndall effect.
Sketch it in your answer
Draw a torch beam entering fog or dust, with scattered rays reaching the observer from the beam path.
Check yourself
Answer the question in your head before opening the answer.
Try it yourself
Why can a torch beam be seen inside a foggy or dusty room?
Think first, then show answerHide answer
Common wrong answer
A common wrong answer is to say the particles make the light stronger.
Why it loses marks: The beam is visible due to scattering, not amplification.
Don't mix this up
Exam tip
Write it in the exam
Each point is worth about one mark. Write point 1 for a 1-mark question and keep adding points as the marks go up.
How CBSE asks it
- 1
Enough for 1 mark
The Tyndall effect is the scattering of light by colloidal particles, making the path of a light beam visible.
- 2
Add for 2 marks
Example: A beam from a torch becomes visible in a dusty room because dust particles scatter the light.
- 3
Add for 3 marks
When a beam of light passes through a medium containing very fine suspended particles, those particles scatter the light sideways.
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