NEET2009PhysicsWave OpticsActual
In Young's double slit experiment, the two slits act as coherent sources of equal amplitude a and of wavelength . In another experiment with the same set up, the two slits are sources of equal amplitude a and wavelength , but are incoherent. The ratio of intensities of light at the mid point of the screen in the first case to that in the second case is
Options
- A2: 1
- B1: 2
- C3: 4
- D4: 3
Correct answer
A. 2: 1
Step-by-step solution
When sources are coherent, intensity at mid point is I_ =(a+a)^2=4 a^2 When sources are incoherent, no interference occurs. Intensity at mid point is aligned & I=I₁+I₂=a^2+a^2=2 a^2 & I_ max I = 4 a^2 2 a^2 =2: 1 aligned