In Young's double slit interference experiment the wavelength of light used is 6000 `overset(circ)(A)` .If the path difference between waves reaching a point P on the screen is `1.5 mu`, then at that point P.

Options

A. Second bright band occurs
B. Second dark band occurs
C. Third dark band occurs
D. Third bright band occurs

Answer

c

Explanation

Path difference for dark fringe,
`Deltax=(2n+1) lambda/2`
`implies 1.5 xx 10^(-6)=(2v+1) (6xx10^(-7))/2`
`implies (2n+1)=(2xx1.5xx10^(-6))/(6xx10^(-7))`
`implies 2n+1=5`
`implies 2n=5-1`
`therefore n=2`