Question

In Young’s double slit experiment using sodium light (λ = 5898Å), 92 fringes are seen. If given colour (λ = 5461Å) is used, how many fringes will be seen

• A. 62
• B. 67
• C. 85
• D. 99

Answer 1

Answer: (D)

99

Answer 2

By using $n_{1}\lambda_{1} = n_{2}\lambda_{2}$ ⇒ $92 \times 5898 = n_{2} \times 5461$

⇒ $n_{2} = 99$