Question

In Young’s double slit experiment distance between two sources is 0.1mm. The distance of screen from the source is 20cm. Wavelength of light used is 5460Å. Then, angular position of the first dark fringe is:

• A. 0.08⁰
• B. 0.16⁰
• C. 0.20⁰
• D. 0.31⁰

Answer 1

Answer: (B)

0.16⁰

Answer 2

Angular position of first dark fringe

$\theta_{1} = (2 \times 1 - 1)\frac{\lambda}{2d} = \frac{\lambda}{2d}$

$= \frac{5460 \times 10^{- 10}}{2 \times 0.1 \times 10^{- 3}} = 2730 \times 10^{- 6}rad$

$= 2730 \times 10^{6} \times \frac{180}{\pi} = 0.16º$