Two point sources of sound are kept at a separation of 10 cm. They vibrate in phase to produce waves of wavelength 5.0 cm. What would be the phase difference between the two waves arriving at a point 20 cm from one source (a) on the line joining the sources and (b) on the perpendicular bisector of the line joining the sources ?

Answer

Zero

Explanation

Path differnece 20 cm which is four times the wavelength so being an integral multiple of wavelength, phase difference is Zero

Due to symmetry phase difference at P is zero.