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

In the interference of two coherent sources of different intensities,the ratio of maximum and minimum intensity is $\frac{I_{\max}}{I_{\min}} = \frac{144}{81}$. What is the ratio of their amplitudes?

Light waves producing interference have their amplitudes in the ratio $3: 2$. The intensity ratio of maximum and minimum of interference fringes is

If the wavelength of light is $4000 \, Å$, then the number of waves in a length of $1 \, mm$ will be:

Define constructive interference. $OR$ Define destructive interference.

The distance between a point source of light and a screen is $60 \ cm$. If this distance is increased to $180 \ cm$,what will be the intensity on the screen compared to the original intensity?