Coherent Source

The two coherent sources of monochromatic light of wavelength lambda are located at a separation lambda . The two sources are placed on a horizontal line and screen is placed perpendicular to the line joining the sources. Find position of the farthest minima from the centre of the sources.

The difference of loudness in decibels (dB) between maximum and minimum intensities of two coherent sound sources as they interfere in space is 20log3 . Find the ratio of intensities of two coherent sound sources:

Two light sources are coherent when