Two coherent sources of intensity ratio $1 : 4$ produce an interference pattern. The fringe visibility will be

The interference pattern is obtained with two coherent light sources of intensity ratio $n$. In the interference pattern,the ratio $\frac{I_{max} - I_{min}}{I_{max} + I_{min}}$ will 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.)

Two coherent sources whose intensity ratio is $64: 1$ produce interference fringes. The ratio of intensities of maxima and minima is

Given below are two statements: one is labelled as Assertion $A$ and the other is labelled as Reason $R$.
Assertion $A$: The phase difference of two light waves changes if they travel through different media having the same thickness,but different indices of refraction.
Reason $R$: The wavelengths of waves are different in different media.
In the light of the above statements,choose the most appropriate answer from the options given below.

To demonstrate the phenomenon of interference,we require two sources which emit radiation of