Question

In young's double slit experiment we get 60 fringes in the field of view of monochromatic light of wavelength 4000Å. If we use monochromatic light of wavelength 6000Å, then the number of fringes obtained in the same field of view are –

• A. 60
• B. 90
• C. 40
• D. 15

Answer 1

Answer: (C)

40

Answer 2

n₁l₁ = n₂l₂ ̃ 60 × 4000 = n₂ × 6000 ̃ n₂ = 40