For example, we have a precise definition of a unit of length called a mile, and have determined that there are about 92,000,000 such miles between the Earth and the Sun. For most systems of units, it...For example, we have a precise definition of a unit of length called a mile, and have determined that there are about 92,000,000 such miles between the Earth and the Sun. For most systems of units, it is convenient to define base units for length, mass, and time; a base electrical unit may also be defined, along with a few lesser-used base units.
If we define a particular unit of length to be the distance that light travels in one second (i.e. a light-second), then the speed of light can be written as 1 light-second/second. We call this system...If we define a particular unit of length to be the distance that light travels in one second (i.e. a light-second), then the speed of light can be written as 1 light-second/second. We call this system of units natural units. The advantage of natural units is that it allows you to drop every instance of c from equations; the downside is that if you want numbers that are not in natural units, then you need to figure out how to reinstate all of the factors of c .
