## Natural units |

in

,physics **natural units**are ofphysical units based only on universalmeasurement . for example, thephysical constants elementary charge *e*is a natural unit of , and theelectric charge speed of light *c*is a natural unit of . a purely naturalspeed has all of its units defined in this way, and usually such that the numerical values of the selected physical constants in terms of these units are exactly 1. these constants are then typically omitted from mathematical expressions of physical laws, and while this has the apparent advantage of simplicity, it may entail a loss of clarity due to the loss of information forsystem of units . it precludes the interpretation of an expression in terms of fundamental physical constants, such as e and c, unless it isdimensional analysis *known*which units (in dimensionful units) the expression is supposed to have. in this case, the reinsertion of the correct powers of*e*,*c*, etc., can be uniquely determined.^{[1]}^{[2]}- introduction
- notation and use
- choosing constants to normalize
- electromagnetism units
- systems of natural units
- see also
- notes and references
- external links

In **natural units** are *e* is a natural unit of *c* is a natural unit of *known* which units (in dimensionful units) the expression is supposed to have. In this case, the reinsertion of the correct powers of *e*, *c*, etc., can be uniquely determined.^{[1]}^{[2]}