If $L$ is the coherence length and $c$ is the velocity of light,the coherence time is

For a distinct interference pattern to be observed,the necessary condition is that the ratio of the intensity of light emission by both sources should be

Two coherent sources produce waves of different intensities which interfere. After interference,the ratio of the maximum intensity to the minimum intensity is $16$. The ratio of the intensities of the waves is:

Two coherent monochromatic beams of intensities $I$ and $4I$ respectively are superposed. The maximum and minimum intensities in the resulting pattern are

Two monochromatic light beams of intensity $16$ and $9$ units are interfering. The ratio of intensities of bright and dark parts of the resultant pattern is

Considering interference between two sources of intensities $I$ and $4I$,the intensity at a point where the phase difference is $\pi$ is $(\cos \pi = -1)$.