Light from two coherent sources of the same amplitude A and wavelength `lambda` illuminates the screen. The intensity of the central maximum is `I_(0)`. If the sources were incoherent, the intensity at the same point will be

Options

A. `4I_(0)`
B. `2I_(0)`
C. `I_(0)`
D. `I_(0)//2`

Answer

D

Explanation

For two coherent sources, `I_(1)=I_(2)`
`I_(max)=(A_(1)+A_(2))^(2)=(sqrt(I_(1))+sqrt(I_(2)))^(2)`
This is given as `I_(0)` for maximum and zero for minimum. If there are two noncoherent sources, there will be no maximum and minimum intensities. Instead of all the intensity `I_(0)` at maximum and zero for minimum, it will be just `I_(0)//2`.