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The refractive indices of the crown glass for blue and red light are 1.51 and 1.49 respectively and those of the flint glass area 1.77 and 1.73 respectively. An isosceles prism of angle  is made of crown glass. A beam of white light is incident at a small angle on this prism. The other flint glass isosceles prism is combined with the crown glass prism such that there is no deviation of the incident light

(i)Determine the angle of the flint glass prism

(ii)Calculate the net dispersion of the combined system

a)

b)

c)

d)



Question ID - 152735 | SaraNextGen Top Answer

The refractive indices of the crown glass for blue and red light are 1.51 and 1.49 respectively and those of the flint glass area 1.77 and 1.73 respectively. An isosceles prism of angle  is made of crown glass. A beam of white light is incident at a small angle on this prism. The other flint glass isosceles prism is combined with the crown glass prism such that there is no deviation of the incident light

(i)Determine the angle of the flint glass prism

(ii)Calculate the net dispersion of the combined system

a)

b)

c)

d)

1 Answer
127 votes
Answer Key / Explanation : (a) -

(a)

(i)When angle of prism is small and angle of incidence is also small, the deviation is given by Net deviation by the prism is zero. So,

Or

Here,  are the refractive indices for crown and flint glass respectively

Hence, and

This gives

Hence, angle of flint glass prism is Negative sign shows that flint glass prism is inverted with respect to the crown glass prism

(ii)Net dispersion due to the two prism is

Net dispersion is

127 votes


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