In a Young's interference experimental arrangement, the incident yellow light is composed of two wavelength 5890Å and 5895Å The distance between of the two slits is `10^(-3)m` and screen is placed 1m away. Upto what order can frings be seen on the screen and how far from the centre of the screen does this occur?

Explanation

The fringes will be invisible when the nth maximum of wavelength `5895 Å` coincides with the (n+1/2) minimum of wavelength 5890 `Å`. Hence
`n beta = (n + 1/2) beta^(.)`
or `n lambda = (n + 1/2) lambda^(.)`
`n(5895) = (n+ 1/2) 5890`
solving we get n=589
So, the fringes will be visible up to the order 589.
Distance from the centre is given by
`x= (n lambda D)/(2d)= (589xx5895xx10^(-10)xx1)/10^(-3) = 0.347m`