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

Answer:

Y = 5.03 x 10⁻³ m = 5.03 mm

Explanation:

Using Young's Double-slit formula:

$Y = \frac{\lambda L}{d}$

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,

$Y = \frac{(6.33\ x\ 10^{-7}\ m)(3.1\ m)}{3.9\ x\ 10^{-4}\ m}$

Y = 5.03 x 10⁻³ m = 5.03 mm