A single slit forms a diffraction pattern,with the first minimum at an angle of 40° from central maximum.Monochromatic light of 410 nm wavelength is used.The same slit,illuminated by a different monochromatic light source,produces a diffraction pattern with the second minimum at a 60° angle from the central maximum.The wavelength of this light,in nm,is closest to:
A)276
B)293
C)309
D)326
E)342

Question

Quizplus · Accepted Answer

For the first minimum, d*sin(theta) = lambda/2. For the second minimum, d*sin(theta) = 2*lambda/2. So, lambda2 = 2*lambda1. lambda2 = 2*410 nm = 820 nm. The closest choice is 826 nm, which is choice A.

A Single Slit Forms a Diffraction Pattern,with the First Minimum