The total energy carried by a light wave when it travels from a rarer to a non-reflecting and non-absorbing medium:

Define constructive interference. $OR$ Define destructive interference.

Two identical light waves, propagating in the same direction, have a phase difference $\delta$. After they superpose, the intensity of the resulting wave will be proportional to

The energy in the phenomenon of interference

If the wavelength of light is $4000 \mathring A$,then the number of waves in $1 \ mm$ length will be

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