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Woher kommt die Energie?

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Almost all energy available on earth comes from a gigantic cosmic fusion reactor high above our heads – from our sun Ever since the origin of the earth (and at least four billion more years) this source of energy has been available to us daily and for free. Just like all other stars which we can see in the night sky the sun consists mostly of hot gas of about three quarters of hydrogen and one quarter of helium In addition, there are about two percent of heavy elements. About half of the total solar mass is concentrated in its centre, the core, which emits the generated energy And this although the core has got only one quarter of the total diameter and so contains 1.5 % of the sun’s total volume only. Here the pressure is billions of times higher than it is in our terrestrial atmosphere and there are temperatures of about 15 million Kelvin. In such conditions hydrogen cores melt together Thus hydrogen is converted into helium by nuclear fusion Part of the atom mass is transformed into energy and released as high-energy photons and low-energy neutrinos. The energy released can be calculated With Albert Einstein’s simple formula the mass can be determined which is converted by the sun into energy during the fusion process. Every second about 5 million tons of matter are sent into space as radiation energy Within one year every square metre of the earth’s surface in Central Europe is hit by an amount of energy of about 000 kwh. Or to put it differently: the sun provides about 0,000 times the energy needed all over the world. is hit by an amount of energy of about 1000 kwh Or to put it differently the sun provides about 10,000 times the energy needed all over the world. Radiation emission is not only typical of the sun but is also relevant for all processes connected with heat Each fire provides energy in the form of rays of light and warmth The temperature of a body is determined by the random movement of its molecules In every water kettle the connection between warmth and movement can be perceived When it is heated, the water inside gets heated, too The movements of the single water molecules get stronger and stronger until eventually the water evaporates Mechanical work or movement, also on the molecular level, generates warmth And this warmth tends to equipartition always moving from hotter to colder body The disorder of molecular movement – called entropy – is thereby increased Thermodynamics has summarized these findings in two main theorems 1. Mechanical work and warmth are two interconvertible forms of energy 2. The entropy in an isolated system cannot decrease but, as a rule, increases These two theorems are valid for all thermodynamic processes for example for energy transformation in power stations Unused energy is eliminated through cooling So the sun releases its energy via radiation While density and temperature in the sun’s core are extremely high they keep decreasing towards the sun’s edge In this process, the many different kinds of radiation are created from radio waves to visible light to X-rays and gamma rays As electromagnetic waves always react like particles as well two different models are used when describing electromagnetic radiation While in the wave theory, the focus is on the different wave lengths with their respective energy, it’s the qualities of single photons that play an important role in the particle theory Sunlight contains the invisible short-wave and therefore energy-rich UV-light the visible light from blue to green to red the invisible infrared light Solar energy that reaches the earth can be stored both for a short and for a long time When our skin is warmed by sunlight or when solar cells absorb the sun rays and convert them into electric current the available energy is stored only for a short time Typical of long-term storage of solar energy are the fossil fuels peat, brown coal, hard coal, natural gas and petroleum Thus, for example, the origin of coal, the energy source used today dates back about 300 million years At that time, in the so-called Carboniferous the climate in large parts of our globe was warm and humid ideal conditions for the growth of many plant species When these withered and did not decompose sufficiently, peat was formed Further deposits increased the pressure and the temperature mounted Over millions of years, eventually carbonisation occurred So the former plant deposits were transformed into first brown and later hard coal

Video Details

Duration: 6 minutes and 22 seconds
Country: Germany
Language: German
Genre: None
Views: 127
Posted by: manfredwolf on May 8, 2010


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