What is diffraction of light? Draw a graph showing the variation of intensity with angle in a single slit diffraction experiment. Write one feature which distinguishes the observed pattern from the double-slit interference pattern.
How would the diffraction pattern of a single slit be affected when:
(i)    the width of the slit is decreased?
(ii)    the monochromatic source of light is replaced by a source of white light? 

Diffraction of light: Phenomenon of bending of light around the comers of an obstacle or aperture is called diffraction.
The intensity distribution wave for diffraction is shown in the diagram below.

In interference, by 2 slits all bright fringes are of same intensity. In diffraction, the intensity of bright fringes decreases with the increase in distance from the central bright fringe.
(i) The diffraction pattern becomes narrower if the width of the slit is decreased.
(ii) A coloured diffraction pattern is obtained if monochromatic source is replaced by white light source. The central band is white therefore, the red fringe is wider than the violet fringe etc.