Ripple Tank Summary
Why Ripple Tanks :
• Real waves (sound, light, radiation) are
difficult to observe
• Properties of waves should be
independent of the type of wave
• Water waves (which are easy to see)
provide a useful analogy for other types of
waves
Wave Properties
• Transmission
• Reflection
• Refraction
• Diffraction
• Interference
Transmission
• The traveling of a wave through a medium
away from a vibrating source
Transmission
• The wavelength of the generated wave
does not change as it travels the length of
the ripple tank
• The speed of the wave remains a constant
Transmission
• If the medium doesn’t change the speed
must remain constant
• A change in the frequency must result in a
change in the wavelength
• An increase in the frequency causes a
shortening of the wavelength
Reflection
• The changing direction of a wave upon
impact with a barrier or object
Reflection
• The speed of the wave, frequency and
wavelength remains unchanged after
reflection
• Only the direction of the wave changes
Reflection
• The direction of the wave changes such
that the angle of incidence is equal to the
angle of reflection
Refraction
• Refraction is the bending of a wave as it
passes from one type of medium into
another type of medium
Refraction
• As the surface waves travel from a deep to
shallow environment the waves will bend
and decrease in wavelength.
Refraction
• Since the frequency of the waves can not
change and the wavelength decreases, the
speed of the wave as it travels from a
deep section to a shallow section must
decrease as well. This causes the waves to
“pile up” on one another.
• Tsunami
Refraction
• This bending of the wave and the
resultant change in speed has
environmental implications!
Diffraction
• The bending of a wave as it either passes
by a barrier / object OR the spreading out
of a wave as it passes through an opening
Diffraction
• Longer wavelengths diffract easier around
a barrier compared to shorter wavelengths
• This is seen in the difference between
light (a short wavelength) and sound (a
long wavelength)
Diffraction
• Waves can also diffract (bend) as they
pass through an opening
• Maximum diffraction occurs when the
width of the slit is close to the wavelength
of the energy
Diffraction
• Diffraction is often used in creating wave
breaks to help dissipate the incoming
energy of the wave
Interference
• The total disturbance within a medium
when more than one wave is present
Interference
• The amplitudes of the waves will add
together as vectors.
• A crest plus a crest forms a much larger
crest
• A trough plus a trough form a deeper
trough
Interference
• If a crest and crest (trough and trough)
add together we end up with constructive
interference
Interference
• If a crest adds to a trough (or trough to a
crest) we end up with destructive
interference
Interference
• In most cases we end up with partial
interference creating a beat.
Interference
• Many objects display an interference
pattern (such as electrons)