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Question
Which is refracted most by a prism : red light or violet light? Explain why?
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Solution
Violet light is refracted the most by a prism. When white light passes through a glass prism, violet colour has the minimum speed and a short wavelength. As violet has a short wavelength, it undergoes the maximum deviation and hence appears at the bottom of the spectrum. On the other hand, red light, which is also a part of the spectrum, has the maximum speed and a longer wavelength, and hence it is the least deviated and forms the upper part of the spectrum.
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RELATED QUESTIONS
State the cause of dispersion of white light passing through a glass prism. How did Newton show that white light of sun contains seven colours using two identical glass prisms. Draw a ray diagram to show the path of light when two identical glass prisms are arranged together in inverted position with respect to each other and a narrow beam of white light is allowed to fall obliquely on one of the focus of the first prism.
Fill in the blank with suitable word:
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What is spectrum? What is the name of glass shape used to produce a spectrum?
What is a rainbow? What are the two conditions necessary for the formation of a rainbow in the sky?
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(b) deflection
(c) dispersion
(d) scattering
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(a) red
(b) orange
(c) violet
(d) blue
The speed of light in air or vacuum is
State the speed of light in (a) air, (b) water, and (c) glass
Out of air and glass, which is optically rarer? Give reason.
Define the term dispersion of light.
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- 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)?
In an experiment to trace the path of a ray of light through a glass prism for different values of angle of incidence a student would find that the emergent ray:
(A) is parallel to the incident ray
(B) perpendicular to the incident ray
(C) is parallel to the refracted ray
(D) bends at an angle to the direction of incident ray
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Say TRUE or FALSE
After passing through a prism, white light splits into a band of seven colours
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.
The angle of deviation through a prism is minimum when
- Incident rays and emergent rays are symmetric to the prism.
- The refracted ray inside the prism becomes parallel to its base.
- The angle of incidence is equal to that of the angle of emergence.
- When the angle of emergence has doubled the angle of incidence.
Choose the correct answer from the options given below:
dispersive power of crown glass? Given that µv = 1.5230, µr = 1.5145
In the following diagram showing dispersion of white light by a glass prism, the colours 'P' and 'Q’ respectively are:
