Two slits at a distance of `1mm` are illuminated by a light of wavelength `6.5xx10^-7m`. The interference fringes are observed on a screen placed at a distance of `1m`. The distance between third dark fringe and fifth bright fringe will be

Options

A. 0.65 mm
B. 1.63 mm
C. 3.25 mm
D. 4.88 mm

Answer

B

Explanation

Distance between third dark fringe and fifth bright fringes =` (5lambdaD)/(d)- ((2 xx 3-1)lambdaD)/(2d)= (5lambdaD)/(2d)= ( 5 xx 6.5 xx 10^(-7) xx 1)/(2 xx 10^(-3))= 16.25 xx 10^(-4)= 1.63mm`