The interference of the two waves at P is fully constructive if their path
length difference DL = |L2-L1|
is an integer multiple of the wavelength l.
DL = n l,
n = 0, 1, 2, ... (fully constructive
The interference of the two waves at P is fully destructive if their path length
difference DL = |L2-L1| is a
half-integer multiple of the wavelength l.
DL = (n+0.5) l,
n = 0, 1, 2, ... (fully destructive
interference) Review wave interference in
Click on S1, S2,or Pand drag them
to change the two waves path length difference DL = |L2-L1|.
Consider a point P where we want to detect the sound from the sources. Let L1
be the distance from P to S1 and L2 be the distance from P
to S2. We assume that L1 and L2 are much
greater than the distance between the sources so that we can approximate the
waves as traveling in the same direction at P.
Consider two sound point sources S1 and S2. S1
emits wave 1 and S2 emits wave 2. The two waves have identical
wavelength l. The phase of wave 1 at S1 is
the same as the phase of wave 2 at S2. Because of this, the two
sources are said to be in phase.