Question

Two slits separated by a distance of 1 mm are illuminated with red light of wavelength 6.5 x 10^–7 metre.

Answer 1

Answer:

Two slits are separated by the distance of 1 mm and can be illuminated with the red light of the wavelength of 6.5 x 10–7 metre. The interference fringes can be observed on the screen placed 1 metre from slits. For the dark fringes, Yn = (2n – 1) * (λd / 2d) or, Y3 = (5/2) * (λd/d). For the bright fringes, Yn = (n* λd)/ d or, Y5 = 5 λd/ d. Hence, the distance between the third dark fringe and fifth fringe on the same side of centre (Y) = Y5 – Y3 = 1.63 mm.

Answer 2

Answer:1.625 mm

Explanation:

d= 10^-3 m

λ=6.5*10^-7 m

D=1 m

We know,  

For distance of dark fringe, y  =(2n-1)λD

​And, for distance of bright fringe, y=nλD /d

​y5-y3 = 5×6.5×10^-7 ×1 / 10^-3  -  (2×3−1)×6.5×10^-7×1  / (2×10^-7)=32.5×10^-4-16.25 ×10^-4 = 16.25 ×10^-4 m

Hence the distance between the third dark fringe and fifth bright fringe is 1.625mm.

hope u understand it ......

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