Problem no. 4
TEAM TALNET
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Discharging an electronic flash unit near
a cymbal will produce a sound from the
cymbal.
Explain the phenomenon and investigate the
relevant parameters.
A photo of cymbal
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Theoretical background
Determining main cause of emitted sound
Measuring of sound
Results
Conclusion
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Flash interacts with the material of the
cymbal
Variants
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By flashing the sound wave is generated
 This sound interact with the cymbal and emits
another sound wave
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Pressure wave
Electromagnetic induction
Light
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A wave based on shift of grossness of air
which is emitted when the flash is
triggered could make the cymbal to emit
sound.
We tried
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clap hands
putting of transparent materials between flash
and cymbal (glass, plastic materials)
flash on thermistor
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When the flash is triggered, a very high
current goes through the gas-filled tube.
Therefore could be generated changing
magnetic field that might take effect on
cymbal.
Experiments
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flashing on razor placed on edge of table in
near nonbalanced state
nonconductor between flash and cymbal
using flash on paper
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All results of experiments are indicating,
that the main cause of this phenomenon
is light (photons).
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We have measured following
characteristics of flash and cymbal
We observed:
difference between different places on cymbal
 decreasing sound intensity with increasing
distance flash from cymbal
 dependence on cymbal´s colour
 comparison energy of released flash and
kinetic energy of falling paperclip
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Distance
We have measured
intensity of sound
emited by cymbal
We have observed
quick decrease of
sound with increasing
distance.
Green line – distance 1 cm
Blue line – distance 6 cm
Red line – distance 17 cm
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We tried to find entries to figure out how
much energy is released from gas-filled
tube when flash is triggered.
We have found these approximated data:
Duration of flash
 Power of flash
 Factor fo conversion from electrical energy to
optical energy
 Flash is acting approximately in area of 1 sr
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Paperclip
We tried to determine
the energy of photons,
which are emitted by
flash. We used following
relations:
Purple – fall of paperclip from 15 cm height
Blue – fall of paperclip from 2 cm height
Red – released flash from 1 cm distance
Emax – potential energy of paperclip in specific height (h)
m – mass of paperclip
g – gravity constant
Ef – aproximated energy of one flash
a – aproximated coefficient
k – number of photons
h – Planck constant
f – frequency of average photon
c – speed of light
λ – wavelength of average photon
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We have determinated, that the main
cause of is light (photons)
We have observed basic relations
between flash and emitted sound.
TEAM TALNET