Question

Red light of wavelength 633 nm from a helium-neon laser passes through a slit 0.390 mm wide. The diffraction pattern is observed on a screen 3.10 m away. Define the width of a bright fringe as the distance between the minima on either side.

Answer 1

Y = 5.03 x 10⁻³ m = 5.03 mm

Step-by-step explanation:

Using Young's Double-slit formula:

`Y = (\lambda L)/(d)`

where,

Y = Fringe Spacing = Width of bright fringe = ?

λ = wavelength = 633 nm = 6.33 x 10⁻⁷ m

L = Screen distance = 3.1 m

d = slit width = 0.39 mm = 3.9 x 10⁻⁴ m

Therefore,

`Y = ((6.33\ x\ 10^(-7)\ m)(3.1\ m))/(3.9\ x\ 10^(-4)\ m)`

Y = 5.03 x 10⁻³ m = 5.03 mm