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Question
Why do you not see a spectrum of colours when light passes through a flat pane of glass?
Solution
When light passes through a flat pane of glass, the refracted light emerges out of the glass pane without any deviation because a glass pane has two sides that are parallel to each other. As the emergent light does not deviate from the original direction by any angle, we do not see the different colours of the light separated out in the form of a spectrum. Therefore, in order to view a spectrum of colours, the incident rays have to fall on an object whose surfaces are not parallel, such as a glass prism (triangular shape).
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RELATED QUESTIONS
Study the following diagrams in which the path of a ray of light passing through a glass prism as traced by four students P, Q, R and S is shown:
The student who has traced the path correctly is
(A) P
(B) Q
(C) R
(D) S
Draw a ray diagram to explain the term angle of deviation.
Which is refracted most by a prism : red light or violet light? Explain why?
Which of the following colour of white light is least deviated by the prism?
(a) green
(b) violet
(c) indigo
(d) yellow
The seven colours in the spectrum of sunlight in order, are represented as :
A ray of white light is passed through a glass prism and a spectrum is obtained on a screen.
- Name the seven colours of the spectrum in order.
- Do the colours have the same width in the spectrum?
- Which of the colour of the spectrum of white light deviates (i) the most, (ii) the least?
The wavelengths of violet and red light are 4000 Å and 8000 Å respectively. Which of the two has the higher frequency?
In the figure, a beam of light consisting of three colours blue, red, and yellow is incident on a prism and on a rectangular glass block respectively. Complete the diagram by drawings of the refracted and emergent rays.
Why do we see a rainbow in the sky only after rainfall?
Assertion: We can see the rainbow in the sky when the rain starts falling after a spell of bright sunlight.
Reason: The rainbow is formed due to the dispersion of light.
