For constructive interference to take place between two monochromatic light waves of wavelength $\lambda$, the path difference should be

Two coherent sources are kept at a distance of $d = 2 \lambda$. $A$ large screen is placed perpendicular to the line joining the sources. Determine the total number of maximas observed on the screen. (Here,$\lambda$ is the wavelength of light.)

What are coherent sources and incoherent sources?

Which phenomena can be explained by the wave nature of light?

As a result of interference of two coherent sources of light,energy is

The phenomenon of interference is shown by