Information about Reversible Process (thermodynamics)
- For articles on other forms of reversibility, including reversibility of microscopic dynamics, see reversibility (disambiguation).
In thermodynamics, a reversible process, or reversible cycle if the process is cyclic, is a process that can be "reversed" by means of infinitesimal changes in some property of the system without loss or dissipation of energy.[1] Due to these infinitesimal changes, the system is at rest during the whole process. Since it would take an infinite amount of time for the process to finish, perfectly reversible processes are impossible. However, if the system undergoing the changes responds much faster than the applied change, the deviation from reversibility may be negligible. In a reversible cycle, the system and its surroundings will be exactly the same after each cycle.[2]
An alternative definition of a reversible process is a process that, after it has taken place, can be reversed and causes no change in either the system or its surroundings. In thermodynamic terms, a process "taking place" would refer to its transition from its initial state to its final state.
Irreversibility
A process that is not reversible is termed irreversible. In an irreversible process, finite changes are made; therefore the system is not at equilibrium throughout the process. At the same point in an irreversible cycle, the system will be in the same state, but the surroundings are permanently changed after each cycle.<ref name="zumdahl" />
Boundaries and states
A reversible process changes the state of a system in such a way that the net change in the combined entropy of the system and its surroundings is zero. Reversible processes define the boundaries of how efficient heat engines can be in thermodynamics and engineering: a reversible process is one where no heat is lost from the system as "waste", and the machine is thus as efficient as it can possibly be (see Carnot cycle).In some cases, it is important to distinguish between reversible and quasistatic processes. Reversible processes are always quasistatic, but the converse is not always true.<ref name="sears" /> For example, an infinitesimal compression of a gas in a cylinder where there exists friction between the piston and the cylinder is a quasistatic, but not reversible process.[3] Although the system has been driven from its equilibrium state by only an infinitesimal amount, heat has been irreversibly lost due to friction, and cannot be recovered by simply moving the piston infinitesimally in the opposite direction.
Engineering archaisms
Historically, the term Tesla principle was used to describe (amongst other things) certain reversible processes invented by Nikola Tesla.[4] However, this phrase is no longer in conventional use. The principle was that some systems could be reversed and operated in a complementary manner. It was developed during Tesla's research in alternating currents where the current's magnitude and direction varied cyclically. During a demonstration of the Tesla turbine, the disks revolved and machinery fastened to the shaft was operated by the engine. If the turbine's operation was reversed, the disks acted as a pump.[5]See also
References
1. ^ Sears, F.W. and Salinger, G.L. (1986), Thermodynamics, Kinetic Theory, and Statistical Thermodynamics, 3rd edition (Addison-Wesley.)
2. ^ Zumdahl, Steven S. (2005) "10.2 The Isothermal Expansion and Compression of an Ideal Gas." Chemical Principles. 5th Edition. (Houghton Mifflin Company)
3. ^ Giancoli, D.C. (2000), Physics for Scientists and Engineers (with Modern Physics), 3rd edition (Prentice-Hall.)
4. ^ Electrical Experimenter, January 1919. p. 615. [1]
5. ^ "Tesla's New Monarch of Machines". New York Herald Tribune, Oct. 15, 1911. (Available online. Tesla Engine Builders Association. [2])
2. ^ Zumdahl, Steven S. (2005) "10.2 The Isothermal Expansion and Compression of an Ideal Gas." Chemical Principles. 5th Edition. (Houghton Mifflin Company)
3. ^ Giancoli, D.C. (2000), Physics for Scientists and Engineers (with Modern Physics), 3rd edition (Prentice-Hall.)
4. ^ Electrical Experimenter, January 1919. p. 615. [1]
5. ^ "Tesla's New Monarch of Machines". New York Herald Tribune, Oct. 15, 1911. (Available online. Tesla Engine Builders Association. [2])
External links
Reversibility can refer to
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- Reversible dynamics - a mathematical dynamical system, or physical laws of motion, for which time-reversed dynamics are well defined.
- * A reversible diffusion — an example of a reversible stochastic process.
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Thermodynamics (from the Greek θερμη, therme, meaning "heat" and δυναμις, dynamis, meaning "power") is a branch of physics that studies the effects of changes in temperature, pressure, and volume on
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Infinitesimals have been used to express the idea of objects so small that there is no way to see them or to measure them. For everyday life, an infinitesimal object is an object which is smaller than any possible measure, whether we measure size, time, chemical concentration, etc.
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In physics, dissipation embodies the concept of a dynamical system where important mechanical modes, such as waves or oscillations, lose energy over time, typically due to the action of friction or turbulence.
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thermodynamic equilibrium when it is in thermal equilibrium, mechanical equilibrium, and chemical equilibrium. The local state of a system at thermodynamic equilibrium is determined by the values of its intensive parameters, as pressure, temperature, etc.
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In thermodynamics, a thermodynamic system, originally called a working substance, is defined as that part of the universe that is under consideration. A real or imaginary boundary separates the system from the rest of the universe, which is referred to as the environment
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A thermodynamic state is the macroscopic condition of a thermodynamic system as described by its particular thermodynamic parameters. The state of any thermodynamic system can be described by a set of thermodynamic parameters, such as temperature, pressure, density, composition,
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irreversible. From this thermodynamics perspective, all natural processes are irreversible. The phenomenon of irreversibility results from the fact that if a thermodynamic system of interacting molecules is brought from one thermodynamic state to another, the configuration or
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Ice melting - a classic example of entropy increasing[1] described in 1862 by Rudolf Clausius as an increase in the disgregation of the molecules of the body of ice.
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In physics, mechanical efficiency is the effectiveness of a machine and is defined as
To show the effectiveness of a machine one must compare its work input to its work output.
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To show the effectiveness of a machine one must compare its work input to its work output.
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A heat engine is a physical or theoretical device that converts thermal energy to mechanical output. The mechanical output is called work, and the thermal energy input is called heat. Heat engines typically run on a specific thermodynamic cycle.
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The Carnot cycle is a particular thermodynamic cycle, modeled on the hypothetical Carnot heat engine, proposed by Nicolas Léonard Sadi Carnot in 1824 and expanded upon by Benoit Paul Émile Clapeyron in the 1830s and 40s.
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A quasistatic process is a thermodynamic process that happens infinitely slowly. In practice, such processes can be approximated by performing them "very slowly".
A quasistatic process often ensures that the system will go through a sequence of states that are
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A quasistatic process often ensures that the system will go through a sequence of states that are
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Friction is the force of two surfaces in contact. It is not a fundamental force, as it is derived from electromagnetic forces between atoms. When contacting surfaces move relative to each other, the friction between the two objects converts kinetic energy into thermal energy, or
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In language, an archaism is the use of a form of speech or writing that is no longer current. This can either be done deliberately (to achieve a specific effect) or as part of a specific jargon (for example in law) or formula (for example in religious contexts).
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Nikola Tesla
Никола Тесл?
I have harnessed the cosmic rays and caused them to operate a motive device.
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Никола Тесл?
I have harnessed the cosmic rays and caused them to operate a motive device.
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alternating current (AC) is an electrical current whose magnitude and direction vary cyclically, as opposed to direct current, whose direction remains constant. The usual waveform of an AC power circuit is a sine wave, as this results in the most efficient transmission of
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The Tesla turbine is a bladeless turbine design patented by Nikola Tesla in 1913. It is referred to as a bladeless turbine because it uses the boundary layer effect and not a fluid impinging upon the blades as in a conventional turbine.
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pump is a device used to move liquids or slurries. A pump moves liquids from lower pressure to higher pressure, and overcomes this difference in pressure by adding energy to the system (such as a water system).
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The Carnot cycle is a particular thermodynamic cycle, modeled on the hypothetical Carnot heat engine, proposed by Nicolas Léonard Sadi Carnot in 1824 and expanded upon by Benoit Paul Émile Clapeyron in the 1830s and 40s.
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In computer science, the Toffoli gate, invented by Tommaso Toffoli, is a universal reversible logic gate, which means that any reversible circuit can be constructed from Toffoli gates. It is also known as the "controlled-controlled-not" gate, which also describes its action.
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Time evolution is the change of state brought about by the passage of time, applicable to systems with internal state (also called stateful systems). In this formulation, time is not required to be a continuous parameter, but may be discrete or even .
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In quantum mechanics, a quantum circuit is a specific model for a quantum computational device. Experiments have already been carried out which can be regarded as implementing a seven-qubit quantum circuit that implements Shor's algorithm.
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Reversible computing includes any computational process that is (at least to some close approximation) reversible, i.e., time-invertible, meaning that a time-reversed version of the process could exist within the same general dynamical framework as the original process.
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Maxwell's demon is an 1867 thought experiment by the Scottish physicist James Clerk Maxwell, meant to raise questions about the possibility of violating the second law of thermodynamics.
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