In a Young's double slit experiment, the slit separation is made to be exactly 4λ. At what angle will the third bright fringe to the side of the central fringe occur? Caution: the angles involved are such that the approximation sinθ ≈ θ is not valid.
A)48.6°
B)75.0°
C)67.5°
D)36.9°
E)43.0°

Question

Quizplus · Accepted Answer

The third bright fringe occurs when the path length difference between the two slits is 3λ. For a slit separation of 4λ, this occurs when sinθ = 3/8. Using a calculator, we find that θ = 48.6°.

In a Young's Double Slit Experiment, the Slit Separation Is