In Young's experiement, the distance between slits is `0.28mm` and distance between slits and screen is `1.4m`. Distance between central bright fringe and third bright fringe is `0.9cm`. What is the wavelength of used light?

Options

A. (a) `5000Å`
B. (b) `6000Å`
C. (c) `7000Å`
D. (d) `9000Å`

Answer

B

Explanation

Position of 3rd bright fringe `x_3=(3Dlambda)/(d)`
`implieslambda=(x_3d)/(3D)=((0.9xx10^-2)xx(0.28xx10^-3))/(3xx1.4)=6000Å`