Coherent monochromatic light of wavelength 632.8 nm passes through a pair of thin parallel slits. The figure shows the central portion of the pattern of bright fringes viewed on a screen 1.40 m beyond the slits. What is the distance between the two slits?

Question

Quizplus · Accepted Answer

Let the distance between the two slits be d.

From the given diagram, we can see that the distance between two consecutive bright fringes is given by:

y = (λD) / d

where λ is the wavelength of the light, D is the distance between the slits and the screen, and y is the distance between two adjacent bright fringes.

We are given λ = 632.8 nm, D = 1.40 m, and y = 1.2 mm (the distance between the first and seventh bright fringes in the central portion of the pattern).

Substituting these values in the above equation, we get:

1.2 x 10^-3 m = (632.8 x 10^-9 m)(1.40 m) / d

Simplifying and solving for d, we get:

d = (632.8 x 10^-9 m)(1.40 m) / (1.2 x 10^-3 m) = 0.281 mm

Therefore, the distance between the two slits is 0.281 mm, which is option C.

Coherent Monochromatic Light of Wavelength 632