The contrast in the fringes in an interference pattern depends on

Considering interference between two sources of intensities $I$ and $4I$,the intensity at a point where the phase difference is $\pi$ is $(\cos \pi = -1)$.

Two light waves of intensities $I_0$ and $9I_0$ superpose at a point to produce a resultant intensity of $7I_0$. Calculate the phase difference between the light waves.

Two identical light waves having phase difference $\phi$ propagate in the same direction. When they superpose,the intensity of the resultant wave is proportional to

When a light wave enters from air into water, which quantity does not change?

Two light waves having the same wavelength $\lambda$ in vacuum are in phase initially. Then the first wave travels a path $L_{1}$ through a medium of refractive index $n_{1}$ while the second wave travels a path of length $L_{2}$ through a medium of refractive index $n_{2}$. After this the phase difference between the two waves is: