From TheBestLinks.com
(Redirected from
Order of magnitude)
An order of magnitude is a factor of ten. For example, two
numbers are said to differ by "three orders of magnitude" if they
differ by three factors of ten, that is one is
approximately 1000 times larger than other.
The order of magnitude of a number is, intuitively speaking, the
number of powers of 10 contained in the number or a close
approximation to it. More precisely, the order of magnitude of a
number can be defined in terms of the logarithm of the number to the
base of 10, usually as the integer part of the logarithm. Thus the
order of magnitude of 400 is 2. The order of magnitude of a number may
also be defined as the exponent of the power of 10 when the number is
represented using scientific notation.
An order of magnitude estimate of a variable whose precise
value is unknown is an estimate rounded in some way to the nearest
power of 10. For example, an accurate order of magnitude estimate for
the human population of the Earth in the year 2000 is 10
billion. An order of magnitude estimate is sometimes also
called a zeroth order approximation.
One way of categorising things in the physical world is by their size. The pages below contain lists of items that are of the same order of magnitude in time, length, area, volume, mass, energy or temperature. This is useful for getting an intuitive sense of the comparative size of things and the overall scale of the universe. SI units are used together with SI prefixes: these were devised with orders of magnitude in mind. Each individual page also gives other units; see also conversion of units.
Orders of magnitude of various quantities
In the following table the different quantities are lined up so that the following are in the same row:
- length and the approximate time taken by light to cross that length
- area of a square and the length of one side
- volume of a cube and the area of one face
- mass of some water and its volume at 4 degrees Celsius or 277.16 K
See also the separate tables for time, length, area, volume, mass, energy, power, temperature and dimensionless numbers.
* Each time shown is linked to that time. However, the time taken for light to cross the corresponding length is 3 times the time shown.
** These are the standard units but this table uses a variety of units, which can make it harder to read.
Units used in the table
The table uses units and prefixes that are commonly recognized:
- Time:
- Length:
- Area:
- Mass:
- Volume:
- Energy:
- millielectronvolt (meV),
- electronvolt (eV)
- megaelectronvolt (MeV)
- gigaelectronvolt (GeV)
- teraelectronvolt (TeV)
- erg
- joule (J)
- kilowatthour kWh
- megawatthour MWh
- gigawatthour GWh
- Temperature:
- nanokelvin (nK)
- microkelvin (µK)
- millikelvin (mK)
- kelvin (K)
See also
External links
de:Größenordnung
es:orden de magnitud
fr:Ordres de grandeur
ja:数量の比較
sl:red velikosti
zh:数量级
Related links
Top visited
0 of
0 links
[no links posted yet]
>> place link >>
Discussion
Last posted
0 of
0 messages
[no messages posted yet]
>> post message >>
Watch
You can
add this article to your own "watchlist" and receive e-mail notification about all changes in this page.