NEET2018PhysicsWave OpticsActual
In Young's double slit experiment the separation d between the slits is 2 mm, the wavelength λ of the light used is 5896   Å and distance D between the screen and slits is 100 cm. It is found that the angular width of the fringes is 0.20 ° . To increase the fringe angular width to 0.21 o (with same λ   and   D ) the separation between the slits needs to be changed to
Options
- A2 . 1   mm
- B1 .9   mm
- C1.8   mm
- D1.7   mm
Correct answer
B. 1 .9   mm
Step-by-step solution
Angular fringe width, θ = λ d , θ 1 θ 2 = d 2 d 1 0.20 0.21 = d 2 2 ⇒ d 2 = 0.20 0.21 × 2 = 1.9 mm