Question

oung's experiment is performed with light of wavelength 502 nm from excited helium atoms. Fringes are measured carefully on a screen 1.50 m away from the double slit, and the center of the 20th fringe (not counting the central bright fringe) is found to be 9.60 mm from the center of the central bright fringe. What is the separation of the two slits?

Answer 1

Answer:

0.00156875 m

Explanation:

y = Distance from the 20th fringe = 9.6 mm

l = Distance to screen = 1.5 m

$\lambda$ = Wavelength = $502\ nm$

m = Number of fringe = 20

We have the relation

$\dfrac{y}{l}=\dfrac{m\lambda}{d}\\\Rightarrow d=\dfrac{m\lambda l}{y}\\\Rightarrow d=\dfrac{20\times 502\times 10^{-9}\times 1.5}{9.6\times 10^{-3}}\\\Rightarrow d=0.00156875\ m$

The seperation of the two slits is 0.00156875 m