Answer: 2.77 cm
Explanation:
Given
Wavelength of light is [tex]\lambda=644\ nm[/tex]
White screen is at a distance of [tex]D=6\ cm[/tex]
Distance between two slits is [tex]d=2783\ mm[/tex]
Distance between two bright fringe is [tex]\frac{\lambda D}{d}[/tex]
So, the distance between 4 th and 2nd bright fringe is
[tex]\Rightarrow y_4-y_2=\dfrac{2\lambda D}{d}\\\\\Rightarrow y_4-y_2=\dfrac{2\times 644\times 10^{-9}\times 6\times 10^{-2}}{2783\times 10^{-9}}\\\\\Rightarrow 2.776\times 10^{-2}\ m\\\Rightarrow 2.77\ cm[/tex]
The distance between 4 th and 2 nd brigth fringe is 2.77 cm.
