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 the interference of two coherent sources of different intensities,the ratio of maximum and minimum intensity is $\frac{I_{\max}}{I_{\min}} = \frac{144}{81}$. What is the ratio of their amplitudes?

"If you illuminate two pinholes using two lamps, the interference pattern will not be observed" - Explain.

In an interference experiment, the path difference between two interfering waves at a point $A$ on the screen is $\lambda/3$, where $\lambda$ is the wavelength of these waves, and at another point $B$ the path difference is $\lambda/6$. The ratio of intensities at points $A$ and $B$ is . . . . . . .

Two coherent sources must have .......

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