Light from a helium-neon laser (λ = 633 nm) is used to illuminate two narrow slits. The

Question

interference pattern is observed on a screen 3.0 m behind the slits. Twelve bright fringes are
seen, spanning a distance of 52 mm. What is the spacing (in mm) between the slits?

Answer 1

We can use the equation for fringe spacing in a double-slit interference pattern:

y = λL / d

where y is the fringe spacing, λ is the wavelength of light, L is the distance between the slits and the screen, and d is the spacing between the slits.

In this case, we are given λ = 633 nm = 0.633 μm, L = 3.0 m, and y = 52 mm = 52 x 10^-3 m.

We can now rearrange the equation to solve for d:

d = λL / y

Substituting the given values:

d = (0.633 x 10^-6 m)(3.0 m) / (52 x 10^-3 m)

Simplifying:

d = (1.899 x 10^-6 m)(1/0.052)

d = 36.52 x 10^-6 m

Converting to mm:

d = 36.52 mm

Therefore, the spacing between the slits is 36.52 mm.