(i) Using Huygens' construction of secondary wavelets explain how a diffraction pattern is obtained on a screen due to a narrow slit on which a monochromatic beam of light is incident normally.(ii) Show that the angular width of the irst diffraction fringe is half that of the central fringe.(iii) Explain why the maxima at `theta=(n+1/2)lambda/a` become weaker and weaker with increasing

Question

(i) Using Huygens' construction of secondary wavelets explain how a diffraction pattern is obtained on a screen due to a narrow slit on which a monochromatic beam of light is incident normally.
(ii) Show that the angular width of the irst diffraction fringe is half that of the central fringe.
(iii) Explain why the maxima at `theta=(n+1/2)lambda/a` become weaker and weaker with increasing `n`.