[Case Study — Young's Double Slit Experiment]

The principle of superposition is used to understand the phenomenon of interference of light waves. It states that at a particular point, the resultant displacement produced by a number of waves is the vector sum of the displacements produced by each wave. Thomas Young devised a way to obtain two coherent sources using two identical pinholes ($S_1$ and $S_2$) illuminated by a single monochromatic pinhole source S. The pattern consists of alternate bright and dark fringes. The fringe width depends on the distance between $S_1$ and $S_2$, the distance of the screen from the plane of $S_1S_2$, and the wavelength of light used.

Q.III. Vandana performs Young's double slit experiment by using orange, green and red lights successively. If the fringe widths measured in the three cases are $\omega_1$, $\omega_2$ and $\omega_3$ respectively, then which of the following is correct?