99 Percentile Qs Bank for JEE MainPhysicsWave Optics
In Young's double slit experiment, red light of wavelength 6000 Å is used and the n th bright fringe is obtained at a point P on the screen. Keeping the same setting, the source of light is replaced by green light of wavelength 5000 Å and now (n+1) th bright fringe is obtained at the point P on the screen. The value of n is
Options
- A4
- B5
- C6
- D3
Correct answer
B. 5
Step-by-step solution
Fringe width, _G=n D d And for n number of fringes, _G=n D d or, _R=n D d For (n+1) th number of fringes, aligned & _G=(n+1) D d & _ R = _ G & or, n _R D d =(n+1) _R D d & n .6000 10⁻¹⁰ D d =(n+1) 5000 10⁻¹⁰ D d or, & 6 n=(n+1) 5 & 6 n=5 n+5 or, 6 n-5 n=5 & n=5 aligned