Question

If path difference becomes $(2n-1)\frac{\lambda }{2}$ then:

• A. white fringe is formed
• B. bright fringe is formed
• C. uniform illumination is obtained
• D. dark fringe is formed

Answer 1

Answer: (D)

Path difference is odd multiple of $\frac{\lambda }{2}.$
Given path difference $=(2n-1)\frac{\lambda }{2}$
which is an odd multiple of $\frac{\lambda }{2}.$
Hence, destructive interference takes place and dark fringe is formed.