In a Young's experiment, two coherent sources are placed `0.90mm` apart and the fringes are observed one metre away. If is produces the second dark fringe at a distance of `1mm` from the central fringe, the wavelength of monochromatic light used would be

Options

A. `60xx10^(-4)` cm
B. `10xx10^(-4) cm`
C. `10xx10^(-5) cm`
D. `6xx10^(-5) cm`

Answer

D

Explanation

`x_(n)=(D)/(d)(2n-1) (lambda)/(2):. x_(2)=(D)/(d)xx1.5 lambda`
`:. lambda=(x_(2)d)/(1.5xxD)=(1xx10^(-3)xx0.9xx10^(-3))/(1.5xx1)`
`=6xx10^(-5) cm`