Question

Suppose that the angle of incidence of plane waves on a double slit with 0.010 mm is β = 20° (instead of the 0° angle we considered in class). If λ = 532 nm, then what angle θ₁ does the m = 1 far-field interference fringe make? Hint: You must take into account the path difference for the light rays incident on the slits. [ans. 23.3°]

1)	Question to be Graded Manually.

Answer 1

This may helps you.

Given that, slit = 0.01mm Angle of incidence (beta) = 20 degree lambda = 532 nm m = 1 For 0 degree incidence angle the condition for interference is d sin theta = m lambda It the incidence angle Ts then, d sin theta = m lambda + d sin Ts for m = 1, Ts = 20 degree, d = 0.01 mm, lambda = 532 nm sin theta_1 = 532 times 10^-9/1 times 10^-7 + 1 times 10^-3/1 times 10^-3 sin 20 = 0.395 theta_1 = sin 6-1 (0.395) = 23.3 degree therefore theta_1 = 23.5 degree This may helps you.

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