Light of wavelength 633 nm from a distant source is incident on a slit 0.750 mm wide, and the resulting diffraction pattern is observed on a screen 3.50 m away. What is the distance between the two dark fringes on either side of the central bright fringe?

y=5.908 mm

Explanation:

Given data

wavelength (λ) = 633nm

d (distant source is incident on a slit) = 0.750mm

D (diffraction pattern is observed on a screen) = 3.50 m

To find

y (What is the distance between the two dark fringes on either side) = ?

Solution

For a dark fringe to form

dy/D=λ

so

y = (Dλ) / d ... eq (1)

Put values of D,λ and d in eq (1) we get

y={3.50 * (633*10⁻⁹) } / (0.750*10⁻³)

y=2.954mm

So the total distance between dark fringes on either side is 2*y

so final distance is

y=5.908 mm