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Question
How will you use two identical prisms so that a narrow beam of white light incident on one prism emerges out of the second prism as white light? Draw the diagram.
Solution
Angle of deflections of the two prisms need to be equal and opposite. While the first prism splits the light in the seven colours due to different angles of deflection, the second prism combines the spectrum along a single ray and the colours again combine to give white light as the emergent light.
RELATED QUESTIONS
Diagrams (a) and (b) in figure below show the refraction of a ray of light of single colour through a prism and a parallel sided glass slab respectively.
- In each diagram, label the incident, refracted, emergent rays and the angle of deviation.
- In what way the direction of emergent ray in the two cases differ with respect to the incident ray? Explain your answer.
Which of the two prism, A made of crown glass and B made of flint glass, deviates a ray of light more?
A ray of light is normally incident on one face of an equilateral glass prism. Answer the following:
What is the angle of incidence on the first face of the prism?
A ray of light is normally incident on one face of an equilateral glass prism. Answer the following:
What is the angle of refraction from the first face of the prism?
In following figure shows two identical prisms A and B placed with their faces parallel to each other. A ray of light of single colour PQ is incident at the face of the prism A. Complete the diagram to show the path of the ray till it emerges out of the prism B.
[Hint: The emergent ray out of the prism B will be parallel to the incident ray PQ]
A ray of light incident at an angle of incidence 48° on a prism of refracting angle 60° suffers minimum deviation. Calculate the angle of minimum deviation.
[Hint: δmin = 2i - A]
What should be the angle of incidence for a ray of light which suffers a minimum deviation of 36° through an equilateral prism?
[Hint: A = 60°, i = (A + δmin)/2]
A monochromatic ray of light is incident on an equilateral prism placed at minimum deviation position with an angle of incidence 45° as shown in the diagram?
- Copy the diagram and complete the path of the ray PQ.
- State two factors on which the angle of deviation depends.
State three factors on which the angle of deviation depends.
Name the colour of white light which is deviated the least on passing through a prism.
