What happens to the interference pattern if the two slits in Young's experiment are illuminated by two independent sources such as two sodium lamps S and S' as shown in figure

Will there be an interference pattern on the screen if the slits in Young's experiment are illuminated by two different sodium lamps emitting light of same frequency and wavelength?

What will happen to interference pattern if two sources of light are not in same phase ?

If the two slits in Young’s double slit experiment are of unequal width, then

Answer the following: (a) what are coherent sources of light ? Two slits in Young's double slit experiments are illuminated by two different sodium lamps emitting light of the same wavelength. Why is no interference pattern observed? (b) Obtain the condition for getting dark and bright fringes in Young's experiment. Hence write the expression for the fringe width. (c) If s is the size of the source and its distance from the plane of the two slits, what should be the criterion for the interference fringes to be seen?

Instead of using two slits as in Youngs experiment, if we use two separate but identical sodium lamps, it will result into