White light is used to illuminate the two slits in Young's double slit experiment. The separation between the slits is b and the screen is at a distance d> > b) from the slits. At a point on the screen directly infront of one of the slits, certain wavelengths are missing. Some of these missing wavelengths are

Options

A. the bright fringes will have unequal spacing .
B. the bright fringes will have unequal brightness.
C. the fringes do not appear .
D. the dark fringes are not perfectly dark .

Answer

D

Explanation

When the slits are of unequal widths , `I_(1) ne I_(2) therefore A ne B`
`I_("min") = (A - B)^(2) ne 0`
i.e, the dark fringes are not perfectly dark .