Question

What must be the ratio of the slit width to the wavelength of light for a single slit to have the first diffraction minimum at 45.0°?

Answer 1

Data: θ = 45°, m = 1

a sin θ = mλ for (m = 1, 2, 3... minima)

Here, m = 1 (First minimum)

∴ a sin 45° = (1)λ

∴ `"a"/lambda = 1/(sin 45^circ)`

∴ `"a"/lambda` = 1.414