Monochromatic green light, wavelength = 554 nm, illuminates two parallel narrow slits 7.7 µm apart. Calculate the angular deviation of the third order, n = 3, bright fringe (a) in radians and (b) in degrees.

Q.Monochromatic green light, wavelength = 554 nm, illuminates two parallel narrow slits 7.7 µm apart. Calculate the angular deviation of the third order, n = 3, bright fringe (a) in radians and (b) in degrees

Ans:
dsinθ=nλ
sinθ=7.7×10−63×550×10−9​ (taking n=3)
≃216×10−3
=0.216
(Hereθ is small so we can take sinθ≈θ)
θ=0.216radian
Now,πradian=1800
⇒3.14radian=1800
So,0.216radian=3.140.216​×1800=12.40