State three charecteristic features which distinguish the interference pattern due to two coherently illuminated sources as compared to that observed in a diffraction pattern due to a sngle slit.

Central fringe obtained in diffraction pattern due to a single slit-

The condition for obtaining maximum in the diffraction pattern due to a single slit is

Why there is no interference pattern observed when two coherent sources are placed far apart?

(a) Define a wavefront. Use Huygen' principle to shown diagrammatically the propagation of a plane wavefront from the intant t_(1)=0 to later time t_(2) . (b) State briefly two features which can distinguish the characteristic features of an interference pattern from those observed in the diffraction pattern due a single slit.

The ratio of intensities of consecutive maxima in the diffraction pattern due to a single slit is

In interference pattern, using two coherent sources of light, the fringe width is …… .

The condition for obtaining secondary maxima in the diffraction pattern due to single slit is

What type of interference pattern will be observed if two coheret sources are placed very close to each other?

Describe any two characteristic feature which distiguish interference and diffraction phenomena. Derive the expression for the intensity at a point of the interference pattern in Young's double slit experiment. (b) In the diffration due to single slit experiment, the aperture of the slit is 3 mm. If monochromatic light of wavelength 620 nm in incident normally on the slit, calculate the separation in between the first order minima and the 3^("rd") order maxima on one side of the screen. The distance between the slit and the screen is 1.5 m.