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

The figure shows two point sources which emit light of wavelength $\lambda$ in phase with each other and are at a distance $d = 5.5 \lambda$ apart along a line which is perpendicular to a large screen at a distance $L$ from the center of the sources. Assume that $d$ is much less than $L$. Which of the following statement$(s)$ is (are) correct?

When two light waves of equal intensity superimpose, the maximum intensity obtained is $I$. If the intensity of one of the waves is quadrupled, then the maximum intensity obtained is

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

The essential condition for obtaining a sustained interference pattern is that the two sources must . . . . . .

The phenomenon of interference is observed in .........