Consider the standing wave,y =A sinπx30sin 2πt  where x   is in cm and  t is in second.  Phase difference (in radians) between two particles at  x=25 cm and  35 cm is

wave starts with a node and wavelength is  2πλ=π30          λ= 60 cm node form at λ2=30 cm 25 and 35 cm are two points on either side of the nodes so phase  differnce is π