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(a) (i) 'Two independent monochromatic sources light cannot produce a sustained interference pattern.' Give reasons. (ii) Light waves each of amplitude "a" and freuency "omega", emanating from two coherent light sources superpose at a point. If the displacement due to these waves is given by y_(1)=acosomegat and y_(2)=acos(omegat+phi) where phi is the phase difference between the two, obtain the expression for the resultant intensity at the point. (b) In Young's double-slit experiment, using monochromatic light of wavelength lamda, the intensity of light at a point on the screen where path difference is lamda, is K units. Find out the intensity of light at a point where path difference is lamda//3. |
| Answer» SOLUTION :(a) (i) To produce a sustained interference pattern the SOURCES of light must be COHERENT sources. HOWEVER, two independent monochromatic sources of light can never be coherent and so cannot produce a sustained interference pattern. | |