The intensities of two coherent sources are $9I$ and $4I$. The intensity at a point where the path difference is $11\lambda$ is:

Two waves having intensity $I$ and $9I$ produce interference. If the resultant intensity at a point is $7I$,what is the phase difference between the two waves?........$^o$

Two monochromatic and coherent point sources of light are placed at a certain distance from each other in the horizontal plane. The locus of all those points in the horizontal plane which have constructive interference will be

The two interfering waves have intensities in the ratio $9 : 4$. The ratio of intensities of maxima and minima in the interference pattern will be

The ratio of the intensities of two waves is $25 : 1$. If interference occurs,then the ratio of the maximum and minimum intensity should be:

Four monochromatic and coherent sources of light,emitting waves in phase of wavelength $\lambda$,are placed at the points $x = 0, d, 2d$,and $3d$ on the $x$-axis. The intensity of the waves reaching a point $P$ far away on the $+x$ axis from each of the four sources is almost the same,and equal to $I_0$. Then,