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.
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News tagged with heat
Scientists Create Material More Insulating than the Vacuum
Dec 10, 2009 |
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(PhysOrg.com) -- With its complete lack of atoms, a vacuum is often considered to be the best known insulator. For this reason, vacuums are regularly used to reduce heat transfer, such as in the lining of ...
Physicists lay the groundwork for cooler, faster computing
Dec 14, 2009 |
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University of Toronto quantum optics researchers Sajeev John and Xun Ma have discovered new behaviours of light within photonic crystals that could lead to faster optical information processing and compact computers that ...
Fujitsu Announces World's First Operation of 100W-Class Amplifiers Employing Carbon Nanotubes
Dec 11, 2009 |
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Fujitsu Laboratories today announced that, using carbon nanotubes as heat-dissipation material in amplifier transistors, Fujitsu has become the first to achieve the successful operation of high-frequency, ...
Ecosystem, vegetation affect intensity of urban heat island effect
Space & Earth / Earth Sciences
Dec 15, 2009 |
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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 ...
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Elusive 'hot' electrons captured in ultra-thin solar cells
Dec 11, 2009 |
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Boston College researchers have observed the "hot electron" effect in a solar cell for the first time and successfully harvested the elusive charges using ultra-thin solar cells, opening a potential avenue to improved solar ...
Scientists discover mechanism behind superinsulation
Dec 14, 2009 |
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(PhysOrg.com) -- Scientists at the U.S. Department of Energy's Argonne National Laboratory have discovered the microscopic mechanism behind the phenomenon of superinsulation, the ability of certain materials ...
A unique geography -- and soot and dust -- conspire against Himalayan glaciers
Space & Earth / Earth Sciences
Dec 15, 2009 |
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"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 ...
Tracking new cancer-killing particles with MRI
Nanotechnology / Nanomaterials
Dec 14, 2009 |
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Researchers at Rice University and Baylor College of Medicine (BCM) have created a single nanoparticle that can be tracked in real time with MRI as it homes in on cancer cells, tags them with a fluorescent ...
3-D microchips for more powerful and environmentally friendly computers
Dec 11, 2009 |
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Not so long ago our computers had a single core which had to be boosted for performance - making each machine into a great central heating system. Beyond 85° C, however, electronic components become unstable. ...
Thermochemical nanolithography now allows multiple chemicals on a chip
Dec 16, 2009 |
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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 ...
New Study Turns Up the Heat on Soot's Role in Himalayan Warming (w/ Video)
Space & Earth / Earth Sciences
Dec 14, 2009 |
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(PhysOrg.com) -- Soot from fire in an unventilated fireplace wafts into a home and settles on the surfaces of floors and furniture. But with a quick fix to the chimney flue and some dusting, it bears no impact ...
Icy moons of Saturn and Jupiter may have conditions needed for life
Dec 15, 2009 |
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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. ...
Global warming could significantly impact US wine and corn production, scientists say
Dec 14, 2009 |
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When it comes to nature, timing is everything. Spring flowers depend on birds and insects for pollination. But if spring-like weather arrives earlier than usual, and flowers bloom and wither before the pollinators appear, ...
Born in beauty: Proplyds in the Orion Nebula (w/ Video)
Dec 14, 2009 |
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(PhysOrg.com) -- A collection of 30 never-before-released images of embryonic planetary systems in the Orion Nebula are the highlight of the longest single Hubble Space Telescope project ever dedicated to ...
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