In a Young's double-slit experiment , the slits are separated by `0.28` mm and screen is placed `1.4` m away . The distance between the central bright fringe and the fourth bright fringe is measured to be `1.2` cm . Determine the wavelength of light used in the experiment .

Options

A. `6xx10^(-7)m`
B. `7xx10^(-7)m`
C. `10^(-7)m`
D. `6xx10^(-5)m`

Answer

A

Explanation

Given, slit width, d = 0.28 mm
`=0.28xx10^(-3)m`
Distance between slit and screen D=1.4 m
`y=1.2cm=1.2xx10^(-2) m, n=4, lambda=?`
For construction interference
`y=nlambda(D)/(d)`
or wavelength of light `lambda=(yd)/(nD)`
`=(1.2xx10^(-2)xx0.28xx10^(-3))/(4xx1.4)=6xx10^(-7)m`