1. What do you understand by deviation produced by prism? Why is it caused? State three factors on which the angle of deviation depends.
2. How does the angle of minimum deviation produced by a prism change with increase in
(i) the wavelength of incident light, and
(ii) the refracting angle of prism?
3. Write a relation for the angle of deviation (δ) for a ray of light passing through an equilateral prism in terms of the angle of incidence (i1), angle of emergence (i2) and angle of prism (A).
4. Name the colour of white light which is deviated
(i) the most, and
(ii) the least, on passing through a prism.
5. A light ray of yellow colour is incident on an equilateral glass prism at an angle of incidence equal to 48° and suffers minimum deviation by an angle of 36°.
(i) What will be the angle of emergence?
(ii) If the angle of incidence is changed to
(a) 30°,
(b) 60°,
state in each case whether the angle of deviation will be equal to, less than or more than 36°?
Answers
Answer:
1.When a monochromatic ray of light passes through a prism, it bends towards the base of the prism due to refraction from the two inclined faces of the prism. ... Deviation produced by a prism is caused by the refraction of light by that prism. The angle of deviation depends upon— 1) Angle of incidence.
2.As we increase the wavelength, angle of deviation decreases. The angle of deviation increases with the increase in the angle of prism.
3.The relation between the angle of incident (i), angle of emergence (e), angle of prism (A) and angle of deviation (δ) for a ray of light passing through an equilateral prism is
δ=(i+e)−A.
4.(i) Violet colour will deviate the most and (ii) red colour will deviate the least.
5.The emergence angle is 48°. The angle of deviation will be less than 36°. The angle of deviation will be more than 36°. Hence, The emergence angle is 48°.
Explanation: