## Light and the Electromagnetic Spectrum

### Energy native the Sun

Nearly every (99.97%) the the energy we have actually on Earth comes from the sun. This amounts to an median of 340 joules/second because that every square meter of the Earth"s surface.Solar power is nuclear energy. It originates from the fusion reactions that occur in the sun. In a combination reaction, two tiny nuclei merge to type the cell nucleus of a larger atom. Part mass is convert to power in the process. Below is a typical combination reaction. An isotope of hydrogen, deuterium or 2H, combine with one more isotope the hydrogen, tritium or 3H, to form helium and also a neutron.

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The deuterium nucleus is composed of 1 proton and also 1 neutron v an atom mass of specifically 2.0. Tritium has actually 1 proton and also 2 neutrons (3.0 amu). The helium nucleus has actually a fixed of 3.98 amu and the free neutron is 1.0 amu. In this reaction some mass, 0.02 amu, is converted right into energy.E = mc2 where c, speed of irradiate = 2.998 x 108 m/secRemember that the joule (J) is the typical unit of energy. We deserve to convert any kind of other unit of energy into joules or kilojoules (kJ). Over there are plenty of online conversions programs to aid with the calculations. For instance 1 joule is equal to 1 (kilogram)(meter)2/(seconds)2.In the last lecture you saw that sun, like any type of other warm object, release its energy in discrete "rays" that have actually some nature of particles and also some nature of waves. We call it electromagnetic radiation.
There is a circulation of energies the the radiation the looks similar to circulation of kinetic energies the atoms and also molecules in ~ a substance. Many graphs of power distributions have actually a comparable shape.Notice the radiation in the visible light range is close come the average energy for the solar spectrum however there is quite a bit of radiation an ext and less energetic than this.You radiate energy, too. The radiation native a human body of around 310 K is in the infrared range.