Question

A monochromatic beam of light falls on YDSE appratus at some angle (say q) as shown in figure. A thin sheet of glass is inserted in front of the lower slit s₂. The central bright fringe (path difference = 0) will be obtained –

• A. At O
• B. Above O
• C. Below O
• D. Anywhere depending on angle q, thickness of plate t and refractive index of glass m

Answer 1

Answer: (D)

Anywhere depending on angle q, thickness of plate t and refractive index of glass m

Answer 2

If dsinq = (µ – 1)t, central fringe is obtained at O.

If dsinq > (µ – 1)t, central fringe is obtained above O.

If dsinq < (µ – 1)t, central fringe is obtained below O.