Answers and Solutions

Answer

Path difference is the difference between the path travelled by the two waves measured in terms of wavelength

Phase difference tells us how one wave is shifted from other in terms of angle

the relation between these two is phase difference is 2pi by lambda times path difference

where lambda is wavelength

Answer

path difference is the difference in path traversed by the two waves , measured in terms of wavelength of the associated wave. It has a direct relation with phase difference. Phase difference decides the nature of interference pattern but phase difference is found out by path difference. Phase difference is related to quantum mechanics. If path difference b/w 2 waves is integral multiple of wavelength, which satisfies condition for constructive interference. Whereas, if path difference b/w 2 waves is odd multiple of half wavelength, it satisfies condition for destructive interference.

whereas phase difference is the difference between some reference point in 2 waves. Its how much one wave is shifted from the other. For eg. at the origin, if one wave's displacement is zero and the other one has some displacement, then there is a shift, which is their phase difference. For eg. sine wave is zero at the origin, but cos wave is not zero at the origin, its zero at pi/2. So the phase difference is pi/2. Infact, cos wave is just the sine wave phase-shifted.

If two waves have zero phase difference, then their crests occur at the same time and so do their troughs. Its like moving together. They will add up (constructive interference).

Answer

There are 2 types of phase difference Spatial(Path) and Temporal(Time or phase). Imagine you and your friend is standing on 2nd floor and third floor of a building but just on top of one another or at the same spot. Then with respect to time you are standing at the same point but in space you are different. This is Temporal. Now if you and your friend are standing in the same floor but at the same line of connect then you are same with space or in the same plane. This is Spatial. Now lets imagine that you both are not standing at the same point in either time or spsace then the difference in between these points is the difference in space and time or path and phase difference.