Physics Help Please!

Question

Light with a wavelength of delta= 567 nm is incident on a single slit of width w = 2.5 micrometers. A screen is located L = 0.15 m behind the slit and an interference pattern has formed on it.

What is the distance between the central bright spot and the first dark fringe, D, in meters?

Answer 1

The angle to the first dark fringe is determined from:

wsinθ = λ (this is the condition for a diffraction minimum from a single slit, but looks like the condition for an interference maximum for 2 slits)

If the angle is small:

θ ≈ tanθ ≈ sinθ = λ/w

The distance on the screen between the central bright spot and the first minimum:

D = Ltanθ ≈ Lλ/w

I assume you can plug in the numbers yourself. Make sure you convert everything to meters first.

Note: the usual notation for a wavelength is lambda λ, not "delta". I hope this helps.