JEE Main 2024 Physics question
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 1ˢᵗ secondary maxima is :
Answer: (B)
Solution
The angular width of a secondary maximum is λ/a, so the linear width = λf/a = (400 × 10⁻⁹ × 1)/(0.2 × 10⁻³) = 2 × 10⁻³ m = 2 mm.