Difference between revisions of "CGS versus SI"

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(Created a table to show the differences between CGS and SI.)
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The [https://en.wikipedia.org/wiki/International_System_of_Units SI or International System of Units] versus the [https://en.wikipedia.org/wiki/Centimetre%E2%80%93gram%E2%80%93second_system_of_units CGS or Centimetre–gram–second] system of units is a constant source of confusion in the field of NMR.  Both are based on the metric system, however the differences can result in quite different forms of the fundamental NMR equations.  An example of this is Tesla versus Gauss units for the magnetic field strength.
 
The [https://en.wikipedia.org/wiki/International_System_of_Units SI or International System of Units] versus the [https://en.wikipedia.org/wiki/Centimetre%E2%80%93gram%E2%80%93second_system_of_units CGS or Centimetre–gram–second] system of units is a constant source of confusion in the field of NMR.  Both are based on the metric system, however the differences can result in quite different forms of the fundamental NMR equations.  An example of this is Tesla versus Gauss units for the magnetic field strength.
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== Units of measurement ==
 +
 +
{|class="wikitable" style="text-align:center;"
 +
|-
 +
! Quantity
 +
! Symbol
 +
! colspan="3" | SI unit
 +
! colspan="3" | CGS unit
 +
! SI to CGS conversion factor
 +
|-
 +
!
 +
!
 +
! Name
 +
! Symbol
 +
! Base unit
 +
! Name
 +
! Symbol
 +
! Base unit
 +
!
 +
|-
 +
! length
 +
|| ''L''
 +
|style="text-align:left;"| metre
 +
||
 +
|| m
 +
|style="text-align:left;"| centimetre
 +
||
 +
|| cm
 +
|| 10<sup>−2</sup>
 +
|-
 +
! mass
 +
|| ''m''
 +
|style="text-align:left;"| kilogram
 +
||
 +
|| kg
 +
|style="text-align:left;"| gram
 +
||
 +
|| g
 +
|| 10<sup>−3</sup>
 +
|-
 +
! time
 +
|| ''t''
 +
|style="text-align:left;"| second
 +
||
 +
|| s
 +
|style="text-align:left;"| second
 +
||
 +
|| s
 +
|| 1
 +
|-
 +
! velocity
 +
|| ''v''
 +
|style="text-align:left;"| metre per second
 +
||
 +
|| m⋅s<sup>−1</sup>
 +
|style="text-align:left;"| centimetre per second
 +
||
 +
|| cm⋅s<sup>−1</sup>
 +
|| 10<sup>−2</sup>
 +
|-
 +
! acceleration
 +
|| ''a''
 +
|style="text-align:left;"| [https://en.wikipedia.org/wiki/Metre_per_second_squared Metre per second squared]
 +
||
 +
|| m⋅s<sup>−2</sup>
 +
|style="text-align:left;"| [https://en.wikipedia.org/wiki/Gal_%28unit%29 Gal]
 +
|| gal
 +
|| cm⋅s<sup>−2</sup>
 +
|| 10<sup>−2</sup>
 +
|-
 +
! force
 +
|| ''F''
 +
|style="text-align:left;"| [https://en.wikipedia.org/wiki/Newton_%28unit%29 Newton]
 +
|| N
 +
|| kg⋅m⋅s<sup>−2</sup>
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|style="text-align:left;"| [https://en.wikipedia.org/wiki/Dyne dyne]
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|| dyn
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|| g·cm·s<sup>−2</sup>
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|| 10<sup>−5</sup>
 +
|-
 +
! energy
 +
|| ''E''
 +
|style="text-align:left;"| [https://en.wikipedia.org/wiki/Joule Joule]
 +
|| J
 +
|| kg⋅m<sup>2</sup>·s<sup>−2</sup>
 +
|style="text-align:left;"| [https://en.wikipedia.org/wiki/Erg erg]
 +
|| erg
 +
|| g·cm<sup>2</sup>·s<sup>2</sup>
 +
|| 10<sup>−7</sup>
 +
|-
 +
! power
 +
|| ''P''
 +
|style="text-align:left;"| [https://en.wikipedia.org/wiki/Watt Watt]
 +
|| W
 +
|| kg⋅m<sup>2</sup>·s<sup>−3</sup>
 +
|style="text-align:left;"| erg per second
 +
|| erg⋅s<sup>−1</sup>
 +
|| g·cm<sup>2</sup>·s<sup>−3</sup>
 +
|| 10<sup>−7</sup>
 +
|-
 +
! magnetic flux density
 +
|| ''B''
 +
|style="text-align:left;"| [https://en.wikipedia.org/wiki/Tesla_%28unit%29 Tesla]
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|| T
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|| 1 kg·s<sup>−2</sup>·A<sup>−1</sup>
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|style="text-align:left;"| [https://en.wikipedia.org/wiki/Gauss_%28unit%29 Gauss]
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|| G
 +
|| esu·cm<sup>−2</sup>
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|| 10<sup>−4</sup>
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|-
 +
! magnetic flux
 +
|| ''H''
 +
|style="text-align:left;"| [https://en.wikipedia.org/wiki/Weber_%28unit%29 Weber]
 +
|| Wb
 +
|| kg·m<sup>2</sup>·s<sup>−2</sup>·A<sup>−1</sup>
 +
|style="text-align:left;"| [https://en.wikipedia.org/wiki/Oersted Oersted]
 +
|| Oe
 +
|| g·cm·s<sup>−2</sup>
 +
|| 1000/4π
 +
|}

Revision as of 14:18, 5 November 2015

This article is a stub. Please help to improve the relax wiki by expanding the article.


Warning  If hard core NMR or physics theory is not to your taste, please do not read any further!

The SI or International System of Units versus the CGS or Centimetre–gram–second system of units is a constant source of confusion in the field of NMR. Both are based on the metric system, however the differences can result in quite different forms of the fundamental NMR equations. An example of this is Tesla versus Gauss units for the magnetic field strength.

Units of measurement

Quantity Symbol SI unit CGS unit SI to CGS conversion factor
Name Symbol Base unit Name Symbol Base unit
length L metre m centimetre cm 10−2
mass m kilogram kg gram g 10−3
time t second s second s 1
velocity v metre per second m⋅s−1 centimetre per second cm⋅s−1 10−2
acceleration a Metre per second squared m⋅s−2 Gal gal cm⋅s−2 10−2
force F Newton N kg⋅m⋅s−2 dyne dyn g·cm·s−2 10−5
energy E Joule J kg⋅m2·s−2 erg erg g·cm2·s2 10−7
power P Watt W kg⋅m2·s−3 erg per second erg⋅s−1 g·cm2·s−3 10−7
magnetic flux density B Tesla T 1 kg·s−2·A−1 Gauss G esu·cm−2 10−4
magnetic flux H Weber Wb kg·m2·s−2·A−1 Oersted Oe g·cm·s−2 1000/4π