Difference between revisions of "Excitement"
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:b : to produce a [[magnetic]] field in <excite a dynamo> | :b : to produce a [[magnetic]] field in <excite a dynamo> | ||
*3: to increase the [[activity]] of (as a living [[organism]]) : [[stimulate]] | *3: to increase the [[activity]] of (as a living [[organism]]) : [[stimulate]] | ||
− | *4: to raise (as an atomic [[nucleus]], an [[atom]], or a [[molecule]]) to a higher [[energy]] level | + | *4: to raise (as an atomic [[nucleus]], an [[atom]], or a [[molecule]]) to a higher [[energy]] level |
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+ | <center>For lessons on the [[topic]] of '''''Excitement''''', follow [http://nordan.daynal.org/wiki/index.php?title=Category:Excitement '''''this link'''''].</center> | ||
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==Description== | ==Description== | ||
'''Excitation''' is an elevation in [http://en.wikipedia.org/wiki/Energy_level energy level] above an [[arbitrary]] baseline [[energy]] state. In [[physics]] there is a specific technical [[definition]] for energy level which is often associated with an atom being excited to an excited state. | '''Excitation''' is an elevation in [http://en.wikipedia.org/wiki/Energy_level energy level] above an [[arbitrary]] baseline [[energy]] state. In [[physics]] there is a specific technical [[definition]] for energy level which is often associated with an atom being excited to an excited state. |
Revision as of 20:31, 20 September 2012
Origin
Latin excitāre, frequentative of exciēre to set in motion, awaken, call forth, instigate, < ex- out + ciēre to set in motion.
Definitions
- 1a : to call to activity
- b : to rouse to an emotional response <scenes to excite the hardest man to pity>
- c : to arouse (as a strong emotional response) by appropriate stimuli <excite enthusiasm for the new regime — Arthur Knight>
- 2a : energize <excite an electromagnet>
- b : to produce a magnetic field in <excite a dynamo>
- 3: to increase the activity of (as a living organism) : stimulate
- 4: to raise (as an atomic nucleus, an atom, or a molecule) to a higher energy level
Description
Excitation is an elevation in energy level above an arbitrary baseline energy state. In physics there is a specific technical definition for energy level which is often associated with an atom being excited to an excited state.
In quantum mechanics an excited state of a system (such as an atom, molecule or nucleus) is any quantum state of the system that has a higher energy than the ground state (that is, more energy than the absolute minimum). The temperature of a group of particles is indicative of the level of excitation (with the notable exception of systems that exhibit Negative temperature).
The lifetime of a system in an excited state is usually short: spontaneous or induced emission of a quantum of energy (such as a photon or a phonon) usually occurs shortly after the system is promoted to the excited state, returning the system to a state with lower energy (a less excited state or the ground state). This return to a lower energy level is often loosely described as decay and is the inverse of excitation.
Long-lived excited states are often called metastable. Long-lived nuclear isomers and singlet oxygen are two examples of this.[1]