The diffraction pattern of a light of wavelength 400 nm diffracting from a slit of width 0 . 2 mm is focused on the focal plane of a convex lens of focal length 100 cm . The width of the 1 st secondary maxima will be :

Step-by-step solution

Width of 1 st secondary maxima = λ a · D Here a = 0 . 2 × 10 - 3 m λ = 400 × 10 - 9 m D = 100 × 10 - 2 = 1 m Therefore, width of 1 st secondary maxima = 400 × 10 - 9 0 . 2 × 10 - 3 × 1 = 2 × 10 - 3 m = 2 mm