Question

Light of wavelength 630 nm falls on two slits and produces an interference pattern in which the third-order bright red fringe is 45 mm from the central fringe on a screen 3.0 m away. What is the separation of the two slits?

Answer 1

Answer:

d $\frac{x}{l}$ = m×  λ⇒ d = λ ×m×l / x

= 630×$10^{-9}$ m × 3×3m/ 45×$10^{-3}$ m

= 1.26×$10^{-4}$m

Explanation:

the above calculation is based on Young’s double slit experiment where the two slits provide two coherent light sources which results either constructive interference or destructive interference when passing through a double slit.