Question

In a young's double slit experiment

a) There is no diffraction

b) Diffraction is so small it is not easily seen

c) Diffraction is readily apparent in the interference pattern

d) Diffraction disappears when the slit separation is integer times the slit width

Answer 1

Diffraction is the spreading of light when light passes through a very small opening comparable to the wavelength of the light. In young's double slit experiment, diffraction occurs in both the slits. In fact, diffraction is the interference of light waves coming from different wave fronts of the same light wave. Thus, diffraction occurs in young's double slit experiment.

Option a) is not correct.

Diffraction pattern can be observed on the screen as long as the slit are very small.

Option b) is not correct.

Diffraction is not observed easily if the slit width is very large.

Option c) is not correct.

Diffraction is not observed when the separation between the slits is integer times the width of the slit. Thus, all the order of the diffraction will be absent. This means diffraction will not occurs instead an interference pattern with uniform width fringes will be observed.

Therefore, Option d) is correct.