The principle of superposition
The resultant displacement at any point is the sum of the separate
displacements due to the two waves Eg: with a slinky coil spring
The principle of superposition
The resultant displacement at any point is the sum of the separate
displacements due to the two waves Eg: with a slinky coil spring
The principle of superposition
The resultant displacement at any point is the sum of the separate
displacements due to the two waves Eg: with a slinky coil spring
supercrest
The principle of superposition
The resultant displacement at any point is the sum of the separate
displacements due to the two waves Eg: with a slinky coil spring
supercrest
Two square waves superposing:
Two square waves superposing:
Two square waves superposing:
Superposition of sine waves:
Superposition of sine waves:
Superposition of sine waves:
A square wave can be made
up from several sine waves
of higher frequencies
Phase changes on reflection
LONGITUDINAL PULSE
TRANSVERSE PULSE
Phase changes on reflection
LONGITUDINAL PULSE
TRANSVERSE PULSE
Phase changes on reflection
LONGITUDINAL PULSE
TRANSVERSE PULSE
Phase changes on reflection
LONGITUDINAL PULSE
TRANSVERSE PULSE
Interference effects
Two dippers in a ripple tank can cause circular wavefronts to re-inforce or cancel:
Re-inforcement
(constructive interference)
Cancellation
(destructive interference)
Interference effects
Two dippers in a ripple tank can cause circular wavefronts to re-inforce or cancel:
Re-inforcement
(constructive interference)
Cancellation
(destructive interference)
Coherent sources (of the same frequency and phase
relationship) produce a stable interference pattern.
Signal
strength
x
Experiments with microwaves:
a) The intensity of the receiver signal decreases with distance from the transmitter.
x
Signal
strength
x
Experiments with microwaves:
a) The intensity of the receiver signal decreases with distance from the transmitter.
b) Microwaves are reflected off metal plates – similar to light on a mirror.
x
Signal
strength
x
x
Experiments with microwaves:
a) The intensity of the receiver signal decreases with distance from the transmitter.
b) Microwaves are reflected off metal plates – similar to light on a mirror.
c) Diffraction occurs at each slit (slit width is of similar magnitude to the wavelength)
Regions of
reinforcement
Experiments with microwaves:
a) The intensity of the receiver signal decreases with distance from the transmitter.
b) Microwaves are reflected off metal plates – similar to light on a mirror.
c) Diffraction occurs at each slit (slit width is of similar magnitude to the wavelength)
d) An interference pattern forms with regions of constructive and destructive interference
Regions of
reinforcement
Experiments with microwaves:
a) The intensity of the receiver signal decreases with distance from the transmitter.
b) Microwaves are reflected off metal plates – similar to light on a mirror.
c) Diffraction occurs at each slit (slit width is of similar magnitude to the wavelength)
d) An interference pattern forms with regions of constructive and destructive interference
Regions of
reinforcement
Regions of
cancellation
Experiments with microwaves:
a) The intensity of the receiver signal decreases with distance from the transmitter.
b) Microwaves are reflected off metal plates – similar to light on a mirror.
c) Diffraction occurs at each slit (slit width is of similar magnitude to the wavelength)
d) An interference pattern forms with regions of constructive and destructive interference
Two loud speakers
emitting the same
note can cause
loud and quiet
areas in front
of the speakers
rarefaction
compressions
Two loud speakers
emitting the same
note can cause
loud and quiet
areas in front
of the speakers
rarefaction
compressions
Regions of reinforcement (LOUD)
Two loud speakers
emitting the same
note can cause
loud and quiet
areas in front
of the speakers
rarefaction
When compressions
(or rarefactions)
arrive in phase from
both speakers,
constructive
interference occurs,
creating a loud region
compressions
Regions of reinforcement (LOUD)
Regions of cancellation (QUIET)