Consider a Young’s double-slit arrangement using monochromatic light of wavelength λ.
(i) Derive an expression for the resultant intensity I at a point on the screen in terms of the path difference Δx.
(ii) Using your result, find the ratio I/Imax when Δx=0.45λ.
(iii) From the value obtained in part (ii), state whether the point corresponds to a bright fringe, a dark fringe, or an intermediate intensity region. Give reasons for your conclusion.