In the experiment of interference of light, the optical paths at a point differ by `73.5` times the wavelenth of blue light of `4400Å` . The nature of the illumination at the same of point using red light of wavelength `6000Å` will be

Options

A. bright
B. dark
C. neither bright nor bark
D. none of these

Answer

C

Explanation

Path diff. `n_(b) lambda_(b)=n_(1) lambda_(r)`
`=73.5xx4.4xx10^(-7)`
`=(323.4xx10^(-7))/(6xx10^(-7)) =53.9`
Since, path diff. `=53.9 lambda`, which is not equal to integral multiple of wavelenght or odd multiple of haf of wavelenght thus, given point is neither, bright nor dark.