Two coherent sources of light can be obtained by

The light beams of intensities in the ratio of $9: 1$ are allowed to interfere. What will be the ratio of the intensities of maxima and minima?

Two waves of same intensity $I_0$ emitted from two sources having same phase difference $(\phi)$. Due to superposition of two waves, the intensity of resultant wave is directly proportional to . . . . . . .

Two coherent sources $S_1$ and $S_2$ are separated by a distance four times the wavelength $\lambda$ of the source. The sources lie along the $y$-axis,whereas a detector moves along the $+x$-axis. Leaving the origin and far-off points,the number of points where maxima are observed is

The difference in the number of wavelengths, when yellow light propagates through air and vacuum columns of the same thickness, is $1$. The thickness of the air column is (Refractive index of air $\mu_a = 1.0003$, Wavelength of yellow light in vacuum $\lambda_0 = 6000 \text{ Å}$)

Light waves are emitted by a common source. For what time interval will the phase remain constant?