Crovas Disc

1
Crovas Disc
Description Each disc consists of a clear
plastic, having non concentric circles ruled upon
its surface. The discs are mounted in case with a
viewing slot, so that the disc may be rotated
about its axis in the case.Both standing and
progressive waves may be displayed by placing the
appropriate disc on the overhead projector.
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Wave Machines
3
Kundts Tube
Description This apparatus demonstrates standing
waves in a horizontal glass tube. The interior is
sprinkled with fine dry cork dust. A speaker is
attached to one end and a signal generator is
used to adjust the frequency to produce standing
waves. The dust gathers at the antinodes of the
standing waves.
4
Rubens Gas Tube
Description A metre long pipe has a series of
small holes drilled equidistant along its length
and is connected to a natural gas supply. At the
other end a horn loudspeaker is driven by a
signal generator and power amplifier combination.
The gas supply is adjusted to give a flame height
of approximately 2 inches. As the frequency is
varied, standing waves are produced, pressure
maxima and minima are formed in the pipe, as
indicated by the height of the flames.
Video www.youtube.com Rubens tube
5
Melde Experiment
Description A light string approximately 2 metres
in length is connected to a motor driven
eccentric cam. The string passes over a pulley
and is attached to a weight. A black cloth may be
placed behind the string to aid visibility. As
the speed of the motor is increased standing
waves are observed. It is possible to obtain 6 or
7 modes and with the aid of a stroboscope the
string motion can be frozen for analysis.
6
Chladni Figures
Description A plate supported at its centre is
mounted a few millimetres above a horn
loudspeaker driven by a signal generator and
public address amplifier. Salt is spread across
the surface and accumulates along nodal lines
upon excitation. Modes of vibration are quite
easily observed.
Video www.youtube.com resonance effect
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Resonance Tube
Description A tuning fork or speaker is placed
above a tube that can be lowered into water. Be
lower the tube into the water or by changing the
frequency produced by the speaker, the natural
frequency of the air in the tube can be matched
to the frequency produced by the tuning fork or
speaker creating a resonance.
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Resonance
Ground Resonance of a Chinook What is a
Chinook? Rear view of ground resonance Side view
of ground resonance Tacoma Bridge
Resonance Tacoma Bridge
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Hearing response and decibels
Test your own hearing http//www.phys.unsw.edu.au/
jw/hearing.html Equal loudness Threshold of
hearing Decibels http//www.phys.unsw.edu.au/
jw/dB.html
10
Ripple Tank
Description The familiar ripple tank utilises
ripples on a water surface to demonstrate the
properties of waves. It consists of a shallow
dish of water, with a transparent base. An
electrically operated vibrator dips into the
water surface and generates the
ripples. Diffraction through a gap can be shown
by placing a slit in front of the source.
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Videos and Applets
www.youtube.com Street Mozart www.youtube.com
Chinook Crash Chinook Resonance test
http//www.chinook-helicopter.com/video/video.html
Tacoma Bridge http//en.wikipedia.org/wiki/Tacom
a_Narrows_BridgeFilm_and_Video_of_collapse Baffl
e board http//147.46.26.158/download/library/down
load.php?sn384
Longitudinal wave applet http//www.mta.ca/faculty
/science/physics/suren/Lwave/Lwave01.html Standin
g wave http//www.walter-fendt.de/ph14e/stwaverefl
.htm Other physics applets http//www.walter-fend
t.de/ph14e/