Let nth minima of 400 nm coincides with mth minima of 560 nm, then
`(2n-1)((400)/(2))= (2m-1) ((560)/(2))` or
`(2n-1)/(2m-1) = (7)/(5) = (14)/(10)=` …..
i.e., 4th minima of 400 nm coincides with 3rd minima of 560 nm. Location of this minima is,
`Y_(1)= ((2xx4-1)(1000)(400xx10^(-9)))/(2xx0.1)= 14mm`
Next 11th minima of 400 nm will coincide with 8th minima of 560 nm. Location of this minima is,
`Y_(2) = ((2xx11-1)(1000)(400xx10^(-9)))/(2xx0.1)= 42 mm`
`:. "Required distance" Y_(2)-Y_(1)=28 mm`.