Question Detail
Question
A slit of width 'a' is illuminated by red light of wavelength 650 nm. For what value of 'a' will the first minima appear at θ = 15°?
Correct Answer
Option D is the correct answer.
Detailed Explanation
For a single slit, the first minimum occurs at a sin θ = λ. a = λ / sin θ = 650e-9 / sin 15° = 650e-9 / 0.2588 = 2.512e-6 m = 2.51 μm.
Hint
Use a sin θ = λ for the first minimum.