For the sustained interference of light,the necessary condition is that the two sources should

If two sources emit light waves of different amplitudes, then in the interference pattern:

Two light beams having intensities $I$ and $9I$ interfere to produce a fringe pattern on a screen. The phase difference between the beams is $\frac{\pi}{2}$ at point $P$ and $\pi$ at point $Q$. The difference between the resultant intensities at $P$ and $Q$ will be ....... $I$.

In an interference pattern obtained by two coherent sources,the variation in intensity is $5\%$ of the average intensity. Find the ratio of the intensities of the two sources.

Two coherent sources produce waves of different intensities which interfere. After interference,the ratio of the maximum intensity to the minimum intensity is $16$. The ratio of the intensities of the waves is:

Two coherent monochromatic light beams of intensities $4 I$ and $9I$ are superimposed. The difference between the maximum and minimum intensities in the resulting interference pattern is $xI$. The value of $x$ is . . . . . . .