Electronvolt: Difference between revisions
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imported>Paul Wormer (New page: {{subpages}} The '''electronvolt (eV)''' is a unit of energy used in many branches of physics. One electronvolt is the amount of potential energy that one electron in an electri...) |
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The '''electronvolt (eV)''' is a unit of [[energy]] used in many branches of [[physics]]. | The '''electronvolt (eV)''' is a unit of [[energy]] used in many branches of [[physics]]. | ||
One electronvolt is the amount of potential energy that one electron in an electric potential field Φ gains when the field Φ is decreased by one volt. The potential energy of an electron in potential Φ is equal to −''e''Φ, where ''e'' is the (positive) [[elementary charge]].<ref>Value of ''e'' retrieved from [http://www.physicstoday.org/codata/fundconstant_2006.pdf Physics Today] on September 19, 2009</ref> Hence when ΔΦ is −1 | One electronvolt is the amount of potential energy that one electron in an electric potential field Φ gains when the field Φ is decreased by one volt. The potential energy of an electron in potential Φ is equal to −''e''Φ, where ''e'' is the (positive) [[elementary charge]].<ref>Value of ''e'' retrieved from [http://www.physicstoday.org/codata/fundconstant_2006.pdf Physics Today] on September 19, 2009</ref> Hence when ΔΦ is −1 volt, the energy gain ΔE = ''e'', and it follows that in [[SI]] units where joule is coulomb times volt: | ||
:1 eV = ''e'' | :1 eV = ''e'' coulomb × 1 volt = 1.602 176 487 × 10<sup>−19</sup> joule . | ||
An equivalent definition of the electronvolt is: the increase in kinetic energy that a single unbound electron gains by passing through an electric potential difference of 1 volt in vacuum. | An equivalent definition of the electronvolt is: the increase in kinetic energy that a single unbound electron gains by passing through an electric potential difference of 1 volt in vacuum. | ||
Revision as of 10:33, 19 September 2009
The electronvolt (eV) is a unit of energy used in many branches of physics.
One electronvolt is the amount of potential energy that one electron in an electric potential field Φ gains when the field Φ is decreased by one volt. The potential energy of an electron in potential Φ is equal to −eΦ, where e is the (positive) elementary charge.[1] Hence when ΔΦ is −1 volt, the energy gain ΔE = e, and it follows that in SI units where joule is coulomb times volt:
- 1 eV = e coulomb × 1 volt = 1.602 176 487 × 10−19 joule .
An equivalent definition of the electronvolt is: the increase in kinetic energy that a single unbound electron gains by passing through an electric potential difference of 1 volt in vacuum.
Note
- ↑ Value of e retrieved from Physics Today on September 19, 2009