A physics quantity calculator with units.

# Usage

* Install this module via `pip install electronvolt`.
* Recommended to use in an interactive python environment, e.g. jupyter notebook.
* Recommended to import via `from electronvolt import *`.

#### You can also run this module online [**HERE**](https://mybinder.org/v2/gh/dw61/electronvolt/HEAD?filepath=online.ipynb).

* This page typically loads within 3 minutes.
* Use shift+enter to run a block of code.
* Run the first block to initialize the calculator.
* Run the second block to feel how it works.

# Demo

Rest mass of an electron

```
>>> from electronvolt import *
>>> me
9.1093837015e-31 * kg
```

Rest energy of the electron, in [SI](https://en.wikipedia.org/wiki/International_System_of_Units) units

```
>>> me * c**2
8.187105776823886e-14 * m**2 * s**-2 * kg
```

In mega electronvolts

```
>>> me * c**2 / MeV
0.5109989499961642
```

This matches the electron rest energy on [this](https://en.wikipedia.org/wiki/Electron_rest_mass) Wikipedia page.

**Rest mass of an electron, with [uncertainties](https://github.com/lebigot/uncertainties)**

```
>>> from uncertainties import ufloat
>>> ume = ufloat(9.1093837015, 0.0000000028) * 1e-31 * kg
>>> ume
(9.1093837015+/-0.0000000028)e-31 * kg
```

Rest energy of the electron, with uncertainties

```
>>> ume * c**2
(8.1871057768+/-0.0000000025)e-14 * kg * s**-2 * m**2
```

This matches the electron rest energy on the [same](https://en.wikipedia.org/wiki/Electron_rest_mass) Wikipedia page.

# Units and Constants

|Name                           |Symbol    |Value      |Unit                         |
|-------------------------------|----------|-----------|-----------------------------|
|                               |          |           |                             |
|**Math Constants**             |          |           |                             |
|                               |`pi`      |3.14159265 |                             |
|Euler's number                 |`euler`   |2.71828183 |                             |
|                               |          |           |                             |
|**Metric Prefixes**            |          |           |                             |
|                               |`yotta`   |1.00E+24   |                             |
|                               |`zetta`   |1.00E+21   |                             |
|                               |`exa`     |1.00E+18   |                             |
|                               |`peta`    |1.00E+15   |                             |
|                               |`tera`    |1.00E+12   |                             |
|                               |`giga`    |1.00E+09   |                             |
|                               |`mega`    |1000000    |                             |
|                               |`kilo`    |1000       |                             |
|                               |`hecto`   |100        |                             |
|                               |`deca`    |10         |                             |
|                               |`deci`    |0.1        |                             |
|                               |`centi`   |0.01       |                             |
|                               |`milli`   |0.001      |                             |
|                               |`micro`   |1.00E-06   |                             |
|                               |`nano`    |1.00E-09   |                             |
|                               |`pico`    |1.00E-12   |                             |
|                               |`femto`   |1.00E-15   |                             |
|                               |`atto`    |1.00E-18   |                             |
|                               |`zepto`   |1.00E-21   |                             |
|                               |`yocto`   |1.00E-24   |                             |
|                               |          |           |                             |
|**Common Prefixes**            |          |           |                             |
|                               |`hundred` |100        |                             |
|                               |`thousand`|1000       |                             |
|                               |`million` |1000000    |                             |
|                               |`billion` |1.00E+09   |                             |
|                               |`trillion`|1.00E+12   |                             |
|                               |          |           |                             |
|**SI Base Units**              |          |           |                             |
|second                         |`s`       |1          |`s`                          |
|meter                          |`m`       |1          |`m`                          |
|kilogram                       |`kg`      |1          |`kg`                         |
|ampere                         |`A`       |1          |`A`                          |
|kelvin                         |`K`       |1          |`K`                          |
|mole                           |`mol`     |1          |`mol`                        |
|candela                        |`cd`      |1          |`cd`                         |
|                               |          |           |                             |
|**Time**                       |          |           |                             |
|                               |`minute`  |60         |`s`                          |
|                               |`hour`    |3600       |`s`                          |
|                               |`day`     |86400      |`s`                          |
|                               |`week`    |604800     |`s`                          |
|                               |`year`    |31557600   |`s`                          |
|millisecond                    |`ms`      |0.001      |`s`                          |
|microsecond                    |`us`      |1.00E-06   |`s`                          |
|nanosecond                     |`ns`      |1.00E-09   |`s`                          |
|                               |          |           |                             |
|**Length**                     |          |           |                             |
|kilometer                      |`km`      |1000       |`m`                          |
|decimeter                      |`dm`      |0.1        |`m`                          |
|centimeter                     |`cm`      |0.01       |`m`                          |
|millimeter                     |`mm`      |0.001      |`m`                          |
|micrometer                     |`um`      |1.00E-06   |`m`                          |
|nanometer                      |`nm`      |1.00E-09   |`m`                          |
|picometer                      |`pm`      |1.00E-12   |`m`                          |
|femtometer                     |`fm`      |1.00E-15   |`m`                          |
|                               |          |           |                             |
|**Frequency**                  |          |           |                             |
|hertz                          |`Hz`      |1          |`s-1`                        |
|kilohertz                      |`kHz`     |1000       |`s-1`                        |
|megahertz                      |`MHz`     |1000000    |`s-1`                        |
|gigahertz                      |`GHz`     |1.00E+09   |`s-1`                        |
|terahertz                      |`THz`     |1.00E+12   |`s-1`                        |
|                               |          |           |                             |
|**Classical Mechanics**        |          |           |                             |
|gravitational acceleration     |`g`       |9.80665    |`m` `s-2`                    |
|newton                         |`N`       |1          |`kg` `m` `s-2`               |
|pascal                         |`Pa`      |1          |`kg` `m-1` `s-2`             |
|joule                          |`J`       |1          |`kg` `m2` `s-2`              |
|watt                           |`W`       |1          |`kg` `m2` `s-3`              |
|                               |          |           |                             |
|**Thermodynamics**             |          |           |                             |
|Planck constant                |`h`       |6.63E-34   |`kg` `m2` `s-1`              |
|reduced Planck constant        |`hbar`    |1.05E-34   |`kg` `m2` `s-1`              |
|Avogadro constant              |`NA`      |6.02E+23   |`mol-1`                      |
|Boltzmann constant             |`kB`      |1.38E-23   |`kg` `m2` `s-2` `K-1`        |
|ideal gas constant             |`R`       |8.31446262 |`kg` `mol-1` `K-1` `m2` `s-2`|
|                               |          |           |                             |
|**Electromagnetism**           |          |           |                             |
|coulomb                        |`C`       |1          |`s` `A`                      |
|volt                           |`V`       |1          |`kg` `A-1` `m2` `s-3`        |
|farad                          |`F`       |1          |`kg-1` `A2` `m-2` `s4`       |
|                               |`Ohm`     |1          |`kg` `A-2` `m2` `s-3`        |
|tesla                          |`T`       |1          |`kg` `A-1` `s-2`             |
|weber                          |`Wb`      |1          |`kg` `m2` `s-2` `A-1`        |
|henry                          |`H`       |1          |`kg` `A-2` `m2` `s-2`        |
|speed of light                 |`c`       |299792458  |`m` `s-1`                    |
|vacuum magnetic permeability   |`mu0`     |1.26E-06   |`kg` `A-2` `m` `s-2`         |
|vacuum electric permittivity   |`epsilon0`|8.85E-12   |`kg-1` `m-3` `s4` `A2`       |
|Coulomb constant               |`k`       |8.99E+09   |`kg` `m3` `s-4` `A-2`        |
|elementary charge              |`e`       |1.60E-19   |`s` `A`                      |
|                               |          |           |                             |
|**Imperial Units**             |          |           |                             |
|inch ('in' is a python keyword)|`in_`     |0.0254     |`m`                          |
|foot                           |`ft`      |0.3048     |`m`                          |
|yard                           |`yd`      |0.9144     |`m`                          |
|mile                           |`mi`      |1609.344   |`m`                          |
|                               |`acre`    |4046.85642 |`m2`                         |
|nautical mile                  |`NM`      |1852       |`m`                          |
|knot                           |`kn`      |0.514444444|`m` `s-1`                    |
|pound-mass                     |`lb`      |0.45359237 |`kg`                         |
|pound-force                    |`lbf`     |4.44822162 |`kg` `m` `s-2`               |
|                               |`slug`    |14.5939029 |`kg`                         |
|                               |`blob`    |175.126835 |`kg`                         |
|                               |          |           |                             |
|**Common Units**               |          |           |                             |
|kilometer per hour             |`kph`     |0.277777778|`m` `s-1`                    |
|miles per hour                 |`mph`     |0.44704    |`m` `s-1`                    |
|                               |`gram`    |0.001      |`kg`                         |
|liter                          |`L`       |0.001      |`m3`                         |
|pound per square inch          |`psi`     |6894.757   |`kg` `m-1` `s-2`             |
|kilowatt-hour                  |`kWh`     |3600000    |`kg` `m2` `s-2`              |
|hectare                        |`ha`      |10000      |`m2`                         |
|                               |          |           |                             |
|**Atomic Physics**             |          |           |                             |
|electron rest mass             |`me`      |9.11E-31   |`kg`                         |
|proton mass                    |`mp`      |1.67E-27   |`kg`                         |
|neutron mass                   |`mn`      |1.67E-27   |`kg`                         |
|atomic mass unit               |`u`       |1.66E-27   |`kg`                         |
|atomic mass of hydrogen        |`mH`      |1.67E-27   |`kg`                         |
|atomic mass of helium          |`mHe`     |6.65E-27   |`kg`                         |
|                               |          |           |                             |
|**Quantum Mechanics**          |          |           |                             |
|Stefan-Boltzmann constant      |`sigma`   |5.67E-08   |`kg` `K-4` `s-3`             |
|Bohr radius                    |`a0`      |5.29E-11   |`m`                          |
|hydrogen ground state energy   |`hground` |-2.18E-18  |`kg` `m2` `s-2`              |
|fine-structure constant        |`alpha`   |0.007297353|                             |
|Rydberg constant               |`Rydberg` |10973731.6 |`m-1`                        |
|                               |          |           |                             |
|**Radioactive Decays**         |          |           |                             |
|becquerel                      |`Bq`      |1          |`s-1`                        |
|curie                          |`Ci`      |3.70E+10   |`s-1`                        |
|millicurie                     |`mCi`     |37000000   |`s-1`                        |
|microcurie                     |`uCi`     |37000      |`s-1`                        |
|                               |          |           |                             |
|**Nuclear Physics**            |          |           |                             |
|electronvolt                   |`eV`      |1.60E-19   |`kg` `m2` `s-2`              |
|kilo-electronvolt              |`keV`     |1.60E-16   |`kg` `m2` `s-2`              |
|mega-electronvolt              |`MeV`     |1.60E-13   |`kg` `m2` `s-2`              |
|giga-electronvolt              |`GeV`     |1.60E-10   |`kg` `m2` `s-2`              |
|tera-electronvolt              |`TeV`     |1.60E-07   |`kg` `m2` `s-2`              |
|electronvolt per speed of light|`eVpc`    |5.34E-28   |`kg` `m` `s-1`               |
|mega-electronvolt per c        |`MeVpc`   |5.34E-22   |`kg` `m` `s-1`               |
|electronvolt per c squared     |`eVpc2`   |1.78E-36   |`kg`                         |
|mega-electronvolt per c squared|`MeVpc2`  |1.78E-30   |`kg`                         |
|                               |          |           |                             |
|**Cosmology**                  |          |           |                             |
|gravitational constant         |`G`       |6.67E-11   |`kg-1` `m3` `s-2`            |
|astronomical unit              |`au`      |1.50E+11   |`m`                          |
|light-year                     |`ly`      |9.46E+15   |`m`                          |
|parsec                         |`pc`      |3.09E+16   |`m`                          |
|megaparsec                     |`Mpc`     |3.09E+22   |`m`                          |
|Hubble parameter               |`H0`      |2.33E-18   |`s-1`                        |
