In a double-slit experiment, green light (5303 Å) falls on a double slit having a separation of 19.44 μm and a width of 4.05 μm. The number of bright fringes between the first and the second diffraction minima is:
Options

Question

In a double-slit experiment, green light (5303 Å) falls on a double slit having a separation of 19.44 μm and a width of 4.05 μm. The number of bright fringes between the first and the second diffraction minima is:

Options

G1 Physics · Accepted Answer

Single-slit minima occur at sinθ=mλ/a, while double-slit bright fringes satisfy sinθ=nλ/d. Between the first and second diffraction minima, d/a<n<2d/a. Here d/a=19.44/4.05=4.8, so n=5,6,7,8,9: five bright fringes. Option D.