For a distinct interference pattern,the condition is that the ratio of intensities of light produced by both sources must be .....

The ratio of maximum to minimum intensity in an interference pattern is $25 : 16$. Calculate the ratio of maximum to minimum amplitude.

Two identical light sources $S_1$ and $S_2$ emit light of same wavelength $\lambda$. These light rays will exhibit interference if

Two light waves of same intensity superpose at point $P$ with a phase difference of $\pi/3$. The resultant intensity at point $P$ will be?

The correct formula for fringe visibility is

Two coherent sources $S_1$ and $S_2$ are separated by a distance four times the wavelength $\lambda$ of the source. The sources lie along the $y$-axis,whereas a detector moves along the $+x$-axis. Leaving the origin and far-off points,the number of points where maxima are observed is