COMEDK2025PhysicsWave OpticsActual
Young's double slit experiment is first done in air and then in a medium of refractive index . If the 8th dark fringe in the medium lies where the 4th bright fringe is in air, then the value of is:
Options
- A1.768
- B1.389
- C1.654
- D1.875
Correct answer
D. 1.875
Step-by-step solution
Position of 4th bright fringe in air: y_ 4,air = 4 D d In medium of refractive index , wavelength becomes ' = . Position of 8th dark fringe in medium: y_ 8,medium = (8 - 0.5) ' D d = 7.5 D d Equating the two positions: 7.5 D d = 4 D d = 7.5 4 = 1.875