For a single slit of width “a”, the first minimum of the interference pattern of «a monochromatic
light of wavelength $\lambda $ occurs at an angle of —$\lambda $/a.At the same angle of $\lambda $/a we get a maximum for two narrow slits separated by a distance “a”. Explain
In the first case, the overlapping of the contributions of the wavelets from two halves of a single slit produces a minimum because corresponding wavelets from two halves have the path difference of λ /2.
In the second case, the overlapping of the wavefronts from the two slits produces first maximum because these wavefronts have the path differences of λ.