Consider a single-slit diffraction pattern caused by a slit of width a. There is a maximum if sin$\theta$is equal to:
A) slightly more than 3$\lambda$/2a
B) slightly less than 3$\lambda$/2a
C) exactly 3$\lambda$/2a
D) exactly$\lambda$/2a
E) very nearly $\lambda$/2a

Question

Quizplus · Accepted Answer

The single-slit diffraction pattern has a maximum when sinθ = mλ/a, where m is an integer representing the order of the maximum. The first maximum occurs when m = 1, so sinθ = λ/a. Rearranging this equation gives λ/a = sinθ, and multiplying both sides by 3 gives 3λ/2a = 3/2 sinθ. Therefore, the maximum occurs when sinθ is slightly less than 3λ/2a, or Choice B.

Consider a Single-Slit Diffraction Pattern Caused by a Slit of Width