Suppose there is a bright fringe at P Would this bright fringe move closer to O, move further away, or be unchanged, t 1.5 marks a) The separation, d, of the slits was reduced? b) The red light was made more intense? c) The red light was replaced with blue light? 3 What does the word "diffraction" mean? (A brief answer is all that is needed)

The distance of a fringe from centre is proportional to wavelength of light

and inversely proportional to separation of slits. The expression for distance x is given by

x = nλ D / d

where λ is wave length, D is screen distance and d is slit separation.

So first option only is correct because

1) the wavelength of blue light is less than that of red

2) Intensity of light does not affect distance of fringe from the centre.

3.

Diffraction symbolises bending of light around sharp edges like slits or boundaries of opaque objects etc. Due to this reason, we do not observe sharp boundary of shadow of an object. Instead around the boundary of shadow, we observe bands of bright and dark color which are also called fringes.

The phenomena of diffraction is explained by wave theory of light.