Question

[
d=
]
fringes width. ( beta=frac{Delta lambda}{2 d} )
[
begin{array}{l}
2 d=frac{D lambda}{beta}
2 d=frac{75 times 5890 times 10^{-8}}{9.424 times 10^{-2}}
=46875 times 10^{-6}
20=46875 mathrm{mcm}
end{array}
]
Teacher's Signature :

# A biprism is placed 5 cm from slit illuminated by sodium light of wavelength 5890 Ă. The width of the fringes obtained on a screen 75 cm from the biprism is 9.424 x 10-2 cm. What is the distance between two coherent sources?

Solution