The fine-structure constant, represented by `alpha`, is the coupling constant which characterizes the strength of the electromagnetic interaction between elementary charged particles.

The fine structure constant is dimensionless and is defined as follows:

`alpha = (k_e*e^2) / (barh *c)` , where `k_e` is the Coulomb Constant, `e` is the elementary charge, `barh` is the reduced Planck constant, and `c` is the speed of light in a vacuum

   `= (1/(4*pi*epsilon_0)) *(e^2/(barh*c))`, were `epsilon_0` is the permittivity of free space

   `= (e^2*c*mu_0) / (2h)` , where `mu_0` is the permeability of free space and `h` is Planck's constant

   `= (c*mu_0) /(2*R_K)` , where `R_K` is the von Klitzing constant

Author: Carol

Notes

This constant is specified with a standard uncertainty (standard deviation) of: 0.000 000 0024 E-3

Arnold Sommerfeld introduced the fine-structure constant in 1916.