Physics (AS & A Level) · May / June 2016 · Paper 22 · Question 5

diffraction: spreading/diverging of waves/light (takes place) at (each) slit/ element/gap/aperture interference: overlapping of waves (from coherent sources at each element) path difference λ/phase difference of 360(°)/2π (produces the first order) [3]

d sinθ = nλ or sinθ = Nnλ d = (2 × 486 × 10–9) / sin 29.7° (= 1.962 × 10–6) number of lines = 510 (509.7) mm–1 [3]