A Young's double slit experiment is performed using a light source that emits two wavelengths, 600 nm and 480 nm . The lowest order of the bright fringe of the 600 nm light that perfectly coincides with a bright fringe of the 480 nm light on the screen is:

Step-by-step solution

For the bright fringes of two different wavelengths to coincide on the screen, their distance from the central maximum must be equal. The position of the n^ th bright fringe is given by y = n D d . Equating the positions for the two wavelengths: n₁ ₁ D d = n₂ ₂ D d n₁ ₁ = n₂ ₂ Let ₁ = 600 nm and ₂ = 480 nm . n₁ 600 = n₂ 480 n₁ n₂ = 480 600 = 4 5 The lowest integer values satisfying this ratio are n₁ = 4 and n₂ = 5 . Therefore, the 4^ th bright fringe of the 600 nm light coincides with the 5^ th bright fringe of the