Wave Medium
Wave Energy
Tsunami Waves
Dulku – Physics 20 – Unit 4 – Topic H
Dulku – Physics 20 – Unit 4 – Topic H
Specific Outcome:
i. I can describe how the speed of a wave depends on the characteristics of
the medium.
ii. I can compare and contrast energy transport by matter and by waves.
Wave Medium and Energy
Wave Medium
The medium is made of the particles that
propagate (vibrate)
The medium can be:
shallow or deep (ex. water)
sparse (low density) or dense (high
density)
A wave can move from one medium to
another, through a change in density
Dulku – Physics 20 – Unit 4 – Topic H
Wave Medium and Energy
Wave Medium
If a wave moves from one density to another,
the following will happen:
frequency stays the same (constant),
because it depends on the source only!
speed and wavelength either increase
together or decrease together
This is consistent with the universal wave
equation (v=fλ) if frequency, f, is constant
Dulku – Physics 20 – Unit 4 – Topic H
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Wave Medium
If a wave moves from shallow to deep water,
or from high density to low density:
wavelength increases
speed increases
Wave Medium
In moving from a less dense medium to a
more dense medium, a portion of the
incident wave is reflected and inverted:
If a wave moves from deep to shallow water,
or from low density to high density:
wavelength decreases
speed decreases
Dulku – Physics 20 – Unit 4 – Topic H
Wave Energy
Dulku – Physics 20 – Unit 4 – Topic H
Tsunami Waves
A matter wave may transfer a large amount
of energy through:
high speed (kinetic energy), or
high amplitude (potential energy)
Tsunami waves are large displacements of
water, deep in the ocean (often caused by an
earthquake or fault line)
An electromagnetic wave (at the speed of
light) may transfer a large amount of energy
through:
low wavelength (high frequency)
high speed, so they have high kinetic
energy
Dulku – Physics 20 – Unit 4 – Topic H
In the deep ocean, tsunamis have:
low amplitude, so they are not usually
visible on the surface
Dulku – Physics 20 – Unit 4 – Topic H
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Tsunami Waves
Tsunami Waves
When approaching shallow water, tsunami
waves slow down and wavelength decreases
In shallow water, a tsunami’s kinetic energy
changes into gravitational potential energy
This is seen as a very high amplitude wave,
which explains why a tsunami is tall only
when near a beach!
Dulku – Physics 20 – Unit 4 – Topic H
Dulku – Physics 20 – Unit 4 – Topic H
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