A source emitting light of wavelengths 480 nm and 600 nm is used in a double slit interference experiment. The separation between the slits is 0.25 mm and the interference is observed on a screen placed at 150 cm from the slits. Find the linear separation between the first maximum (next to the central maximum) corresponding to the two wavelengths.

Answer

B

Explanation

We know that the first maximum (next to central maximum) occurs at `y=(lamdaD)/d`
`Given that lamda_1=480nm`
`lamda_2=600nm`
D=150cm=1.5m`
and `d=0.25mm`
`=0.25xx10^-3m`
so, `y_1=(Dlamda_1)/d`
`=((1.5)xx480xx10^-9)/(0.25xx10^-3)`
`=2.88mm`
`y_2=((1.5)xx600xx10^-9)/(0.25xx10^-3)`
so the separation between these two bright fringes is given by
`:. Separation `=y_2-y_1`
`=3.60-2.88=0.72mm.