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Question
Why do you not see a spectrum of colours when light passes through a flat pane of glass?
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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
Describe an activity to show that colours of white light splitted by a glass prism can be recombined to get white light by another identical glass prism. Also draw ray diagram to show the recombination of the spectrum of white light.
Study the following figure in which a student has marked the angle of incidence (∠i), angle of refraction (∠r), angle of emergence (∠e), angle of prism (∠A) and the angle of deviation (∠D). The correctly marked angles are
(a) ∠A and ∠i
(b) ∠A, ∠i and ∠r
(c) ∠A, ∠i, ∠e and ∠D
(d) ∠A, ∠i, ∠r and ∠D
In the formation of spectrum of white light by a prism:
which colour is deviated most?
When a beam of white light is passed through a prism, it splits to form lights of seven colours. Is it possible to recombine the lights of seven colours to obtain the white light again? Explain your answer.
What are the seven colours seen in a rainbow?
The colour of white light which suffers the maximum bending (or maximum refraction) on passing through a glass prism is:
(a) yellow
(b) orange
(c) red
(d) violet
The splitting up of white light into seven colours on passing through a glass prism is called:
(a) refraction
(b) deflection
(c) dispersion
(d) scattering
- A beam of monochromatic light undergoes minimum deviation through an equiangular prism, how does the beam pass through the prism, with respect to its base?
- If white light is used in the same way as in part (a) above, what change do you expect in the emergent beam?
- What conclusion do you draw about the nature of white light in part (b)?
Draw a labeled ray diagram to illustrate the dispersion of a narrow beam of white light when it passes through a glass prism.
A student has to trace the path of a ray of light through a glass prism. List four precautions he should observe for better results.
Write three conditions necessary to obtain a pure spectrum on a screen. Name the instrument in which the conditions stated by you are fulfilled.
Suggest one way, in each case, by which we can detect the presence of Infrared radiations.
The process of separation of light into its component colours while passing through a medium is called _______.
Which of the following is a natural phenomenon which is caused by the dispersion of sunlight in the sky?
The splitting of white light into its component colours is called ____________.
In the following diagram showing dispersion of white light by a glass prism, the colours 'P' and 'Q’ respectively are:
State the colour which bends:
- The most.
- The least while passing through a glass prism.
