Coherent light with wavelength 599 nm passes through two very narrow slits with separation of 20 μm, and the interference pattern is observed on a screen located at a distance of 3.0 m from the slits. where will the second order dark fringe above the center of central bright fringe will form?

134.77 mm

Explanation:

Wave length of light λ = 599 x 10⁻⁹ m

Slit separation d = 20 x 10⁻⁶ m

Screen distance D = 3 m

Distance of second dark fringe from centre

= 1.5 x λ D / d  

Putting the  values given above

distance =

= 134.77 x 10⁻³ m

= 134.77 mm.

they should be similar or the same

d.7.5cm is your answer