Answer:562.5 nm
Explanation:
Given
Screen is separated from double slit [tex]\left ( D\right )by 1.2m[/tex]
Distance between two slits[tex]\left ( d\right ) is 0.030 mm[/tex]
Second order bight fringe is 4.5 cm from center line
i.e.
[tex]y_2=\frac{2\lambda D}{d}[/tex]
[tex]\lambda =\frac{y_2\times d}{2D}[/tex]
[tex]\lambda =\frac{4.5\times 3\times 10^{-7}}{2.4}[/tex]
[tex]\lambda =562.5nm[/tex]
Distance between adjacent bright fringe
[tex]\Delta y=\frac{\lambda D}{d}=22.5\times 10^{-3} mm[/tex]
