White light is used in a YDSE with `D = 1 m` and `d = 0.9 mm`. Light reaching the screen at position `y = 1 mm` us passed through a prism and its spectrum is obtained. Find the missing lines in the visible region of this spectrum.

Explanation

`Delta x = (yd)/(D) = 9 xx 10^(-4) xx 1 xx 10^(-3) m = 900nm`
For minima, `Delta x = (2 n - 1) lambda//2`
`implies lambda = (2 Delta x)/((2n - 1)) = (1800)/((2n - 1))`
`= (1800)/(1) , (1800)/(3) , (1800)/(5) , (1800)/(7) ,…`
Of these, 600 nm and 360 nm lie in the visible range. Hence, these will be the missing lines in the visible spectrum.