Main page | New articles & Tasks |
The Energy Portal Welcome to Wikipedia's Energy portal, your gateway to energy. This portal is aimed at giving you access to all energy related topics in all of its forms.
|
Page contents: Selected article • Selected image • Selected biography • Did you know? • General images • Quotations • Related portals • Wikiprojects • Major topics • Categories • Help • Associated Wikimedia |
In physics, energy (from Ancient Greek ἐνέργεια (enérgeia) 'activity') is the quantitative property that is transferred to a body or to a physical system, recognizable in the performance of work and in the form of heat and light. Energy is a conserved quantity—the law of conservation of energy states that energy can be converted in form, but not created or destroyed. The unit of measurement for energy in the International System of Units (SI) is the joule (J).
Common forms of energy include the kinetic energy of a moving object, the potential energy stored by an object (for instance due to its position in a field), the elastic energy stored in a solid object, chemical energy associated with chemical reactions, the radiant energy carried by electromagnetic radiation, and the internal energy contained within a thermodynamic system. All living organisms constantly take in and release energy.
Due to mass–energy equivalence, any object that has mass when stationary (called rest mass) also has an equivalent amount of energy whose form is called rest energy, and any additional energy (of any form) acquired by the object above that rest energy will increase the object's total mass just as it increases its total energy.
Human civilization requires energy to function, which it gets from energy resources such as fossil fuels, nuclear fuel, or renewable energy. The Earth's climate and ecosystems processes are driven by the energy the planet receives from the Sun (although a small amount is also contributed by geothermal energy). (Full article...)
The effects of global warming are expected to include sea level rise, floods, drought and changes in the frequency and intensity of extreme weather events. Other effects may include changes in agricultural yields, reduced summer streamflows, species extinctions and increases in the ranges of disease vectors.
Concentrations of greenhouse gases are now considerably higher than at any time during the last 650,000 years, the extent of the ice core record. It is believed that CO2 concentrations were last this high 20 million years ago. The primary international agreement on combating global warming is the Kyoto Protocol, which covers more than 160 countries and over 55% of global greenhouse gas emissions. The United States, the world's largest greenhouse gas emitter; Australia; and Kazakhstan have refused to ratify the treaty. China and India, two other large emitters, have ratified the treaty but are exempt from cutting emissions. International talks on a successor to the treaty, which ends in 2012, have begun.
Photo credit: Björn Appel
A solar furnace can be used to generate electricity, melt steel or make hydrogen fuel.
In 1831, Faraday began his great series of experiments in which he discovered electromagnetic induction. He established that a changing magnetic field produces an electric field, a relation mathematically modelled by Faraday's law. Faraday later used the principle to construct the electric dynamo, the ancestor of modern power generators. He went on to investigate the fundamental nature of electricity, concluding in 1839 that, contrary to opinions at the time, only a single "electricity" exists, and the changing values of quantity and intensity (voltage and charge) would produce different groups of phenomena.
Some historians refer to Faraday as the best experimentalist in the history of science. Despite this his mathematical ability did not extend so far as trigonometry or any but the simplest algebra. He nevertheless possessed the ability to present his ideas in clear and simple language. During his lifetime, Faraday rejected a knighthood and twice refused to become President of the Royal Society.
WikiProjects connected with energy:
Other WikiProjects that may be of interest:
National energy supply, use & conservation
National electricity sector
Politics, economics, environment
Energy sources
Energy-related design
Scientific usage
Puzzled by energy?
Can't answer your question?
Don't understand the answer?
For further ideas, to leave a comment, or to learn how you can help improve and update this portal, see the talk page.
The following Wikimedia Foundation sister projects provide more on this subject:
© MMXXIII Rich X Search. We shall prevail. All rights reserved. Rich X Search