To observe a stationary interference pattern formed by two light waves, it is not necessary that they must have

To observe a stationary interference pattern formed by two light waves, which of the following is not a necessary condition:

To obtain steady or sustained interference pattern, two sources of light should be

What will happen to interference pattern if two sources of light are not in same phase ?

For steady interference, two two sources of light must be

For steady interference of light, the two sources of light must be

Give any two characteristics of interference of light waves.

For observing interference in thin films with a light of wave length lambda the thickness of the film :