and show whySolution1 In case if slit width w is kept consta

and show why?

Solution

1)

In case if slit width w is kept constant and seperation d between the slits is increased the fringes become closer and enevelop pattern remains unchanged. therefore, more interference maxima will fall in central enevelop.

In case if the distance between the slits are varied and slit width is kept constant, the spacing between the two consecutive maxima changes. THe certain interference maxima will be missing depending on the relative values of w and d.

The direction of interference maxima is given by

(w+d)sin (theta) = + or - n (lamda)

direction for the diffraction minima due to each single slit are

esin(theta)=+ or - m (lamda)

If values of w and d are satisfied for the same value of theta, certain interference maxima will be overlapped by the diffraction minimaum and will dissapaear.

If slit width is increased the envelope of the fringe pattern changes such that the central peak is sharper but the fringe spacing remains unchanged as it depends on the slit seperation d,