While performing Young's double slit experiment, the given changes were made. If the initial fringe spacing was 'x', then the fringe spacing after the changes will be

Explanation

In Young's double slit experiment, the fringe spacing (Δy) is given by the formula Δy = λL/d, where λ is the wavelength of light, L is the distance from the slits to the screen, and d is the distance between the slits. If the fringe spacing changes to x/4, it suggests a fourfold increase in the slit distance or a fourfold decrease in the wavelength. The correct option is D (x / 4.) because it aligns with a scenario where the slit distance has increased significantly, affecting the fringe pattern. Options A, B, and C are incorrect as they do not reflect the necessary conditions to achieve a quarter of the original fringe spacing.