Wave Interference
When several waves are in the same location , the waves
combine to produce a single new wave that is different from the
original wave.
1) Constructive Interference: when two
waves interact and the resultant wave has a
larger amplitude (Part A, Figure below)
2) Destructive Interference: when two waves
interact and the resultant wave has a smaller
amplitude (Part B, Figure below)
INTERFERENCE IN LIGHT WAVES:
(transverse electromagnetic)
• Create colorful displays
• Ex- soap bubbles- pg 476
– You see many colors because the light is bouncing
off different parts of the bubble (creating differing
wavelengths)
– These waves interfere constructively in some
places and destructively in others.
– These different frequencies are interpreted by
your eyes to create many different colors .
INTERFERENCE IN LIGHT WAVES:
(transverse)
INTERFERENCE IN SOUND WAVES:
(longitudinal mechanical)
• If two waves are “out of sync” they cause “beats” of louder
noise (when they are in line and have constructive
interference) and then quiet (when they are opposite and
destructive interference occurs)
• http://library.thinkquest.org/19537/Physics5.
html
STANDING WAVES:
• Form when a wave is reflected at the boundary of
a medium.
– Interference of the original wave with the reflected
wave causes the medium to vibrate in a stationary
pattern that resembles a series of loops.
– The wave appears to be standing still, but it is not!!!
(actually moving in both directions)
• NODES– Lie at points where the crests of the original waves
meet the trough of the reflected waves, causing
complete destructive interference.
• ANTINODES– Midway between the nodes lie points of maximum
vibration
– This is where the crests of both waves meet creating
complete constructive interference.
• http://paws.kettering.edu/~drussell/Demos/s
uperposition/superposition.html