1. The problem statement, all variables and given/known data Laser light of wavelength λ is incident onto a pair of narrow slits of width a and spacing d Write down an expression for the intensity as a function of angle of the angle measured from the central axis, θ, in the far-*‐field 2. Relevant equations 3. The attempt at a solution I thought it was just the product of single and double slit diffraction, i.e.... I= I0cos2(∏dsinθ/λ)(sin(∏asinθ/λ)/∏asinθ/λ))2 but the answer was I= 4I0cos2(∏dsinθ/λ)(sin(∏asinθ/λ)/∏asinθ/λ))2 im not sure where this 4 has come from?? also how would I show if d=a then this formula turns into the double slit pattern.??