Q. 30

# In a Young’s double slit interference experiment the fringe pattern is observed on a screen placed at a distance D from the slits. The slits are separated by a distance d and are illuminated by monochromatic light of wavelength λ. Find the distance from the central point where the intensity falls to (a) half the maximum, (b) one fourth of the maximum.

Answer :

(a)Given, separation between the slits

The distance between the screen and the slit,

Wavelength of light, .

Let the maximum intensity be and the intensity at y be .

Given,

therefore, path difference,

(b)Here, when intensity is (1/4) times the maximum,

therefore, path difference,

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