Question

Consider the situation shown in figure (17-E6). The two slits S₁ and S₂ placed symmetrically around the central line are illuminated by a monochromatic light of wavelength λ. The separation between the slits is d. The light transmitted by the slits falls on a screen ∑₁ placed at a distance D from the slits. The slit S₃ is at the central line and the slit S₄ is at a distance z from S₃. Another screen ∑₂ is placed a further distance D away from ∑₁. Find the ratio of the maximum to minimum intensity observed on ∑₂, if z is equal to

(a) z=λD/2d (b) λD/d (c) λD/4d

Answer 1

i) When, z = λD/2d, at S₄, minimum intensity occurs (dark fringe)

ii) When, z = λD/2d, At S₄, minimum intensity occurs. (dark fringe)