"Effective Mass" is used in the motional equation for electrons in solid state bodies, depending on the wavenumber and corresponding to its velocity and energy level.
Applicable units are those of quantitykind:Mass
http://en.wikipedia.org/wiki/Effective_mass_(solid-state_physics)
"Effective Mass" is used in the motional equation for electrons in solid state bodies, depending on the wavenumber and corresponding to its velocity and energy level.
$m^* = \hbar^2k(\frac{d\varepsilon}{dk})$, where $\hbar$ is the reduced Planck constant, $k$ is the wavenumber, and $\varepsilon$ is the energy of the electron.
http://www.iso.org/iso/catalogue_detail?csnumber=31897