Question

Light from a helium-neon laser (λ= 633 nm) is used to illuminate two narrow slits. The interference pattern is observed on a screen 3.1 m behind the slits. Eleven bright fringes are seen, spanning a distance of 52 mm.
(i) Sketch the interference pattern in detail.
(ii) What is the spacing (in mm) between the slits?

Answer 1

Answer:

d = 0.377 mm

Explanation:

given data

λ = 633 nm

interference pattern =  3.1 m

spanning a distance = 52 mm

solution

we get here spacing between the slits d that is express as

d = $\frac{m\lambda L}{\Delta y}$  ................1

put here value and we get

and here distance at which the pattern is being observed is much greater than the separation between the maximum of order 10

for bright fringes from m=0 to m=10

d = $\frac{10 \times (633\times 10^{-9})\times 3.1}{(52\times 10^{-3})}$  

d = 0.000377  

d = 0.377 mm