1. The problem statement, all variables and given/known data Suppose that light is incident on a double slit apparatus, with a slit separation d at an angle of ∅ (phi) to the normal (see attached diagram). A) Derive an equation; in terms of the variables d, ∅, θ, integers m, and the wavelength λ of the incoming light; that yields the location of the maxima (constructive interference). B) If ∅ = 20°, what is the angle θ of the m = 0 central maximum? C) If the wavelength of the incoming light is 500 x 10-9 m, the slit separation is 0.25 mm, and the distance to the screen is D = 10 m, how far form the central (m = 0) maximum is the nearest (m - 1) maximum? 2. Relevant equations Constructive interference: δtot = mλ d sin θ = mλ d sin ∅ = mλ 3. The attempt at a solution Diagram of situation is attached. I'm confused on this one. I understand constructive interference but am a little confused on the derivation. I know that the wavelengths corresponding to ∅ and θ both travel an extra distance of d sin ∅ and d sin θ which then must correspond to mλ but how are they connected all together? Any input is appreciated.