Heat
hideIn physics and thermodynamics, heat is the process of energy transfer from one body or system to another due to a difference in temperature. In thermodynamics, the quantity TdS is used as a representative measure of the (inexact) heat differential δQ, which is the absolute temperature of an object multiplied by the differential quantity of a system's entropy measured at the boundary of the object.
A related term is thermal energy, loosely defined as the energy of a body that increases with its temperature. Heat is also loosely referred to as thermal energy, although many definitions require this thermal energy to actually be in the process of movement between one body and another to be technically called heat (otherwise, many sources prefer to continue to refer to the static quantity as "thermal energy"). Heat is also known as "Energy".
Energy transfer by heat can occur between objects by radiation, conduction and convection. Temperature is used as a measure of the internal energy or enthalpy, that is the level of elementary motion giving rise to heat transfer. Energy can only be transferred by heat between objects - or areas within an object - with different temperatures (as given by the zeroth law of thermodynamics). This transfer happens spontaneously only in the direction of the colder body (as per the second law of thermodynamics). The transfer of energy by heat from one object to another object with an equal or higher temperature can happen only with the aid of a heat pump, which does work.
For more information about Heat, read the full article at
Wikipedia.
This text uses material from Wikipedia and is available under the GNU Free Documentation License.
News tagged with heat
Researcher Uses Graphene Quilts to Keep Things Cool
Nanotechnology / Nanomaterials
22 hours ago |
4.6 / 5 (10) |
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(PhysOrg.com) -- University of California, Riverside Professor of Electrical Engineering and Chair of Materials Science and Engineering Alexander Balandin is leading several projects to explore ways to use ...
Ecosystem, vegetation affect intensity of urban heat island effect
Space & Earth / Earth Sciences
Dec 15, 2009 |
5 / 5 (2) |
0
NASA researchers studying urban landscapes have found that the intensity of the "heat island" created by a city depends on the ecosystem it replaced and on the regional climate. Urban areas developed in arid and semi-arid ...
Panasonic Starts Mass-Production of High-Capacity 3.1 Ah Lithium-ion Battery
Dec 18, 2009 |
2 / 5 (2) |
2
Panasonic Corporation developed a 18650-type high-capacity 3.1 Ah lithium-ion battery and began mass production of the battery this December. The new 3.1 Ah battery has a nickel positive electrode and an energy density of ...
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A unique geography -- and soot and dust -- conspire against Himalayan glaciers
Space & Earth / Earth Sciences
Dec 15, 2009 |
4 / 5 (2) |
1
"So many disparate elements, both natural and man-made, converge in the Himalayas," said William Lau, a climatologist from NASA's Goddard Space Flight Center in Greenbelt, Md. "There's no other place in the ...
Hot Electrons Could Double Solar Cell Power Efficiency
Dec 18, 2009 |
4.2 / 5 (12) |
2
Scientists have experimentally verified a theory suggesting that hot electrons could double the output of solar cells. The researchers, from Boston College, have built solar cells that successfully use hot ...
Thermochemical nanolithography now allows multiple chemicals on a chip
Dec 16, 2009 |
4.5 / 5 (4) |
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(PhysOrg.com) -- Scientists at Georgia Tech have developed a nanolithographic technique that can produce high-resolution patterns of at least three different chemicals on a single chip at writing speeds of ...
Icy moons of Saturn and Jupiter may have conditions needed for life
Dec 15, 2009 |
4.8 / 5 (16) |
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(PhysOrg.com) -- Scientists once thought that life could originate only within a solar system's "habitable zone," where a planet would be neither too hot nor too cold for liquid water to exist on its surface. ...
An Advance in Superconducting Magnet Technology Opens the Door for More Powerful Colliders
Dec 16, 2009 |
4.8 / 5 (11) |
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(PhysOrg.com) -- Preparing for as much as a 10-fold increase in the Large Hadron Collider's luminosity within the next decade, U.S. scientists and engineers have demonstrated a powerful magnet based on an ...
Physicists see through the opaque with 'T-rays'
Dec 18, 2009 |
4.2 / 5 (10) |
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"T-rays" may make X-rays obsolete as a means of detecting bombs on terrorists or illegal drugs on traffickers, among other uses, contends a Texas A&M physicist who is helping lay the theoretical groundwork to make the concept ...
Global warming likely to be amplified by slow changes to Earth systems
Space & Earth / Earth Sciences
Dec 20, 2009 |
2.6 / 5 (38) |
43
Researchers studying a period of high carbon dioxide levels and warm climate several million years ago have concluded that slow changes such as melting ice sheets amplified the initial warming caused by greenhouse ...
Miracle light: Can lasers solve the energy crisis?
Dec 15, 2009 |
4.3 / 5 (13) |
4
Next year will mark the 50th birthday of the laser, one of the most productive and widely used mega-inventions of the last century. Scientists hope that 2010 also will see the launch of laser technology's greatest challenge: ...
New results from a terra-ific decade in orbit
Space & Earth / Earth Sciences
Dec 15, 2009 |
5 / 5 (1) |
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December 18, 2009, marks the tenth year since the launch of Terra, one of NASA's "flagship" Earth observing satellites. But the decade is more than just a mechanical milestone. With each additional day and ...
Computer-simulated Thunderstorms with Ice Clouds Reveal Insights for Next-generation Computer Models
Space & Earth / Earth Sciences
Dec 18, 2009 |
4.2 / 5 (5) |
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(PhysOrg.com) -- Computer simulations of thunderstorms using data from a field campaign in Australia confirm that the "ice-phase" cloud processes in climate models contribute most to the wide discrepancy between ...
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