Optics Question 1149

Question: In Fresnel’s biprism (μ=1.5) experiment the distance between source and biprism is 0.3 m and that between biprism and screen is 0.7m and angle of prism is 1 . The fringe width with light of wavelength 6000AA will be

[RPMT 2002]

Options:

A) 3 cm

B) 0.011 cm

C) 2 cm

D) 4 cm

Show Answer

Answer:

Correct Answer: B

Solution:

β=(a+b)λ2a(μ1)α

where a = distance between source and biprism = 0.3 m b = distance between biprism and screen = 0.7 m. a = Angle of prism = 1°, m = 1.5, λ = 6000 x 10^-10 m

Hence, β=(0.3+0.7)×6×1072×0.3(1.51)×(1o×π180) = 1.14 x 10^-4 m = 0.0114 cm.



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