In Young's double-slit experiment, the separation between the slits is halved, and the distance between the slit and screen is doubled. The fringe width is:

Explanation

In Young's double-slit experiment, if the separation between the slits is halved and the distance between the slits and screen is doubled, the fringe width becomes quadrupled. Here's why:Fringe width formula:The fringe width (β) in a double-slit experiment is given by β = (λD)/d, where λ is the wavelength of light, D is the distance between the slits and the screen, and d is the separation between the slits. Changes in the experiment:The separation between the slits (d) is halved, so the new separation is d/2. The distance between the slits and screen (D) is doubled, so the new distance is 2D. New fringe width:Substituting these changes into the formula, the new fringe width (β') becomes: β' = (λ * 2D) / (d/2) = (4λD)/d = 4β. Conclusion:Therefore, the new fringe width is four times the original fringe width, meaning it is quadrupled.