Connected to the output of an audio amplifier, plasma speakers vary the size of a plasma glow discharge, corona discharge or electric arc which then acts as a massless radiating element, creating the compression waves in air that listeners perceive as sound.
42.
Your definition, a compression wave which does not actually move the air, and what they might be talking about, perhaps more properly called a " blast wave ", where the air itself is blown away, potentially at much higher speeds.
43.
While light and sound are both waves, they are very different things-sound is compression waves in a medium ( air, usually ), light doesn't have a medium, it's just self-propagating electric and magnetic fields.
44.
So pushing one end of the poll means that the force you impart into one end of the poll will be transmitted ( probably as a compression wave ) to the other end of the pole, and some velocity less than the speed of light ( probably substantially less too ).
45.
In a similar way, compression waves in solids depend both on compressibility and density just as in liquids but in gases the density contributes to the compressibility in such a way that some part of each attribute factors out, leaving only a dependence on temperature, molecular weight, and heat capacity ratio which can be independently derived from temperature and molecular composition ( see derivations below ).
46.
:There are toys ( called things like Air bazooka ) which send a single large pulse of compression wave outwards . . . and giant versions of those like this are able to knocks over stuff like empty soda cans-but that's not like a continuous sound wave, material actually travels along the path of the compression-you can see this happen when people use such machines to shoot smoke rings.
47.
This wave moves at the speed of sound through both the intake and tailpipe air masses . ( Because these air masses are significantly elevated in temperature as a result of earlier cycles, the speed of sound in them is much higher than it would be in normal outdoor air . ) When a compression wave reaches the open end of either tube, a low pressure rarefaction wave starts back in the opposite direction, as if " reflected " by the open end.
48.
Sound is transmitted by compression waves moving through a medium such as air; your eardrum vibrates when these waves hit it, and these vibrations are converted to a meaningful form by your brain ( I can't say how, biology never really grabbed me ) .'Light'is the visible portion of the electromagnetic spectrum, transmitted by photons ( which are tiny packets of energy with fascinating properties which aren't worth going into at the level of this discussion ).
49.
:: : : The speed of light doesn't limit density because the wave speed equations that depend on density break down if the speed of the individual material particles becomes relativistic . ( They probably break down well before then, actually; most such equations apply only in the limit of small ( read : slow ) oscillations . ) In other words, a material wave travelling faster than light would require some propogating influence ( e . g ., electrostatic repulsion in most compression waves; particle collisions in gases ) or material particle to be travelling faster than light, and that's already impossible without talking about density .-- Tardis 03 : 10, 25 July 2006 ( UTC)
