Question

Describe biprism experiment to find the wavelength of monochromatic light. Draw the necessary ray diagrams.

Answer 1

Answer:

Young's Slits is a variant on the Fresnel Biprism experiment.

Explanation:

Two thin prisms are joined at their bottoms to produce an isosceles triangle in the Fresnel biprism. A single wavefront impinges on both prisms, with the left segment refracted right and the right segment refracted left. Interference arises in the superposition area because two virtual sources exist.

Here  d

is determined by placing a converging lens between the biprism and the screen and forming real images of the virtual slits on the screen. From the magnification formula,

d 1 d = v 1 u 1

 a n d d 2 d = v 2 u 2 = u 1 v 1 ,  We find that  d = √ d 1 d 2

Putting this into the Young’s Slits equation gives  

λ = S √ d 1 d 2 L

Given  

v ω − v g = 2.7 ×10 7 m / s ,

μ g = 1.5 , μ ω = 1.33

∵ v ω = C μ ω = C 1.333

∵ v g = C μ g = C 1.5

 ∴ v ω − v g = C μ ω − C μ g

= C [ 1 1.333− 1 1.5 ] ⇒ 2.7 × 10 7 = C [ 1.5 − 1.333 1.5 × 1.333 ]

⇒ C = 323272455.1 = 3.23 × 10 8 m / s