In a Young's double slit experiment, the slits are separated by 0.28 mm and the 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.

Explanation

`d=0.2mm=0.28xx10^(-3)m, D=1.4m" "n=4, y_(n)=1.2xx10^(-2)m`
`y_(n)=(n lamda D)/d, lamda=(y_(n) . D)/(nD)" " lamda=(1.2xx10^(-2)xx0.28xx10^(-3))/(4xx1.4)=6xx10^(-7)m=600nm`