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

For dark fringe `x=(2n-1)(lamdaD)/(2d)`
`thereforelamda=(2xd)/((2n-1)D)=(2xx10^(-3)xx0.9xx10^(-3))/((2xx2-1)xx1)`
`lamda=0.6xx10^(-6)m=6xx10^(-5)cm`