NTA Abhyas JEE Main2020PhysicsWave OpticsPractice
In Young's double-slit experiment, the distance between slits is d = 0 . 25 cm and the distance of the screen D = 120 cm from the slits. If the wavelength of light used is λ = 6000 A ° and I 0 is the intensity of central maximum, then the minimum distance of the point from the centre, where the intensity is I 0 2 is k × 10 - 5 m . What is the value of k ?
Correct answer
7.2
Step-by-step solution
I = I 0 2 = I 0 cos 2 ϕ 2 cos ϕ 2 = 1 2 ϕ 2 = π 4 ϕ = π 2 2 π λ y D d = π 2 y = λ D 4 d = 6 0 0 0 × 1 0 - 10 × 1.2 4 × 0.25 × 1 0 - 2 = 7 · 2 × 1 0 - 5 m