interference Questions

When exposed to sunlight, thin films of oil on water often exhibit brilliant colours due to the phenomenon of:

Two periodic waves of intensities $I_1$ and $I_2$ pass through a region at the same time in the same direction. The sum of the maximum and minimum intensities is:

In the Young's double-slit experiment, the intensity of light at a point on the screen where the path difference is $\lambda$ is $K$, ($\lambda$ being the wave length of light used). The intensity at a point where the path difference is $\lambda /4$, will be:

Two slits in Young’s experiment have widths in the ratio $1:25$. The ratio of intensity at the maxima and minima in the interference pattern, $\frac{I_{max}}{I_{min}}$ is:

The intensity at the maximum in a Young’s double slit experiment is $I_0$. Distance between two slits is $d=5\lambda$, where $\lambda$ is the wavelength of light used in the experiment. What will be the intensity in front of one of the slits on the screen placed at a distance $D=10d$?

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