Problem no. 4

TEAM TALNET

Discharging an electronic flash unit neara cymbal will produce a sound from the cymbal.

Explain the phenomenon and investigate the relevant parameters.

A photo of cymbal

Theoretical background Determining main cause of emitted sound Measuring of sound Results Conclusion

Flash interacts with the material of the cymbal

Variants By flashing the sound wave is generated

This sound interact with the cymbal and emits another sound wave

Pressure wave Electromagnetic induction Light

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 clap hands putting of transparent materials between flash

and cymbal (glass, plastic materials) flash on thermistor

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 flashing on razor placed on edge of table in

near nonbalanced state nonconductor between flash and cymbal using flash on paper

All results of experiments are indicating, that the main cause of this phenomenon is light (photons).

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

We have measured intensity of sound emited by cymbal

We have observed quick decrease of sound with increasing distance.

Green line – distance 1 cmBlue line – distance 6 cmRed line – distance 17 cm

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

We tried to determine the energy of photons, which are emitted by flash. We used following relations:

Purple – fall of paperclip from 15 cm heightBlue – fall of paperclip from 2 cm heightRed – released flash from 1 cm distance

Emax – potential energy of paperclip in specific height (h)m – mass of paperclipg – gravity constantEf – aproximated energy of one flasha – aproximated coefficientk – number of photonsh – Planck constantf – frequency of average photonc – speed of lightλ – wavelength of average photon

We have determinated, that the main cause of is light (photons)

We have observed basic relations between flash and emitted sound.

TEAM TALNET