Low-energy states of matter Classical states
In the 20th century, however, increased understanding of the more exotic properties of matter resulted in the identification of many additional states of matter, none of which are observed in normal conditions. The three classical states of matter are solid, liquid and gas. States are usually distinguished by a discontinuity in one of those properties: for example, raising the temperature of ice produces a discontinuity at 0☌, as energy goes into a phase transition, rather than temperature increase. States of matter are distinguished by changes in the properties of matter associated with external factors like pressure and temperature. Like a neon sign, the excited oxygen and nitrogen atoms give off light.įollow LiveScience on Twitter. Those particles, being charged, follow magnetic field lines and move toward the poles, where they collide with and excite atoms in the air, mostly oxygen and nitrogen. The solar wind is a stream of charged particles (mostly protons), which hit Earth's magnetic field.
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The plasma excites red, green and blue phosphors, which combine to give off specific colors, according to eBay.Īnother use for plasma is in plasma globes, which are full of noble gas mixes that produce the colors of the "lightning" inside them when an electric current ionizes the gas.Īnother example of plasma is in the auroras that surround the poles when the sun is particularly active. An electrical current is passed through the gas, which causes it to glow. A gas - usually argon, neon or xenon - is injected into a sealed gap between two glass panels. The excited electrons that drop back into their previous energy levels emit photons – the light we see in a neon sign or fluorescent lamp. The gas inside the bulb becomes a conductive plasma. In those cases a gas (neon for signs) is subjected to a high voltage, and the electrons are either separated from the atoms of the gas or pushed into higher energy levels. One place you can see plasmas in action is in a fluorescent light bulb or neon sign. (Image credit: Kheng Guan Toh / ) Plasmas in action Since no material can contain it, scientists and engineers have turned to magnetic fields to do the job.Ī newly patented device could use heated, ionized air to stop shock waves generated by explosions. To create the conditions for fusion, one needs very hot plasma - at millions of degrees. Most fusion power research is focused on doing just that. It's possible that Alfvén waves are the reason the temperature of the solar corona– also a plasma – is millions of degrees, while on the surface, it is only thousands.Īnother characteristic of plasmas is that they can be held in place by magnetic fields. There's no real analogue to this in ordinary gases. An Alfvén wave happens when the magnetic field in a plasma is disturbed, creating a wave that travels along the field lines. One such wave is called an Alfvén wave, named for Swedish physicist and Nobel laureate Hannes Alfvén. That in turn means waves become more important when discussing what goes on in a plasma. Speaking of electrostatic interactions, because particles in a plasma – the electrons and ions – can interact via electricity and magnetism, they can do so at far greater distances than an ordinary gas. Most plasmas aren't dense enough for particles to collide with one another very often, so the magnetic and electrostatic interactions become more important. A magnetic field can create a population of very fast particles, for example. That doesn't happen in a plasma, especially in an electric or magnetic field. That's because in a gas the molecules, like billiard balls, hit each other and transfer energy between them. So if you have gas in a container and let it cool to room temperature, all the molecules inside will, on average, be moving at the same speed, and if you were to measure the speed of lots of individual particles you'd get a distribution curve with lots of them moving near the average and only a few either especially slowly or quickly. In an ordinary gas, all the particles will behave roughly the same way. And since moving charges make magnetic fields, plasmas also can have them. Being made of charged particles, plasmas can do things gases cannot, like conduct electricity.
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