can light create sound?

Question

i have pondered this question for ages. if the electromagnetic wave creates vibrations in all planes (unpolarised light) its more than likely light radiation displaces particles, and isnt that the definition of sound?

Answer 1

Visible light creates sound indirectly, for example the dawn chorus of birdsong when the sun rises and the reflection of laser light from CDs.

Light is an example of electromagnetic energy a vibration in the electric and magnetic fields. Sound is a vibration or movement of molecules which transfers to our ears. They are both vibrations but by vibrations in different 'media'.

Heat (aka infra red radiation, another type of electromagnetic energy) does move molecules - rapid heating may result in a rapid expansion. molecules moving apart and setting up a sound wave as they do so.

Answer 2

The frequency of most phonon modes in solids and pressure waves in gases and liquids are factors of at least 10^-8 smaller than the frequency of photons. So what happens is that photons excite things that can resonate at their frequency, typically electrons in bonds, or vibrational/rotational modes of molecules. If you get enough vibrational/rotational modes going, they can collisional excite phonon modes in the auditory range of frequencies, but the coupling efficiency is not great under most conditions unless you are physically damaging the material by vaporizing it (e.g., running a 50 mJ-30 ps pulse from a mode-locked Nd:YAG laser into a piece of aluminum makes a very loud bang, but that is from the aluminum ionizing as the pulse hits it and the subsequent shock wave propagating outwards from the surface, it's not really the photons directly exciting the phonon modes of the aluminum). I vaguely recall there are crystals or materials or gases maybe, that under the right conditions will resonate at acoustic frequencies when hit by light of the appropriate wavelength, but in general it is not easy to do.

I would google "phonon photon interaction" or maybe "phonon photon coupling" or something like that to find out more. You might also try "surface acoustic wave spectroscopy" which is a little different than what you are asking about, but does involve phonon-photon interaction and might lead you to more relevant information.

I forgot about a common acousto-optical device that also works on the principle of sound interacting with light, google "Bragg cell" Bragg cell frequencies are well above the auditory range (i.e., tens of mega-Hertz), but they are acoustic in nature.

Answer 3

A sound is the results of a disturbamce of a medium. Light also cause a disturbance of a medium . The motion of light and the motion of sound both involve oscillating moving forces.
We sense Light energy with our eyes and we sense Sound energy with our ears. The two scenarios even thought they are related ,actually function at two different Intensity of Energy level.

To obstain sound out of light Signals we need a transducer and an amplifier and an out put to speakers. This technology had been developed and is the world of lasers and fiber optics.

Answer 4

Not directly: the frequency of light is far above that of audible sound.
It is of course possible to turn light energy into sound. A pulse of laser light on the right material creates intense heat, causing sudden expansion of the material and a shock wave that generates sound (in simple language, it goes "sput"!).

Answer 5

light does not vibrate. It can displace particles but unlike the way that particles are dislplaced by a sound wave.

Answer 6

You can make a small mirror suspended from a light-weight string move if you focus the right frequency of light on one of the courners. So I don't see why you couldnt do that with the hammer of a bell.

Answer 7

LIGHT itself, doesnt make noise, not noticable anyway.

Indirect effects do make noise, if focused light burns a spot u hear the heat,

if light is burning the flint in a lightbulb it makes noise,

etc.

Answer 8

To transfer kinetic energy you need mass. Light doesnt have any mass.
Light cannot create sound.

Answer 9

Not normally, but it is possible to make a light-to-sound transducer.

Answer 10

Yes, light a firework.