Editing Fermi energy (section)

==Formula and typical values==
The Fermi energy for a three-dimensional, non-[[Special relativity|relativistic]], ''non-interacting'' ensemble of [[identical particles|identical]] [[spin-1/2|spin-{{frac|1|2}}]] fermions is given by<ref>{{Cite book |title=[[Introduction to Solid State Physics]] |last=Kittel |first=Charles |date=1986 |publisher=Wiley |language=en |chapter=Ch. 6: Free electron gas}}</ref>
<math display="block">E_\text{F} = \frac{\hbar^2}{2m_0} \left( \frac{3 \pi^2 N}{V} \right)^{2/3},</math>
where ''N'' is the number of particles, ''m''<sub>0</sub> the [[rest mass]] of each fermion, ''V'' the volume of the system, and <math>\hbar</math> the reduced [[Planck constant]].

===Metals===
Under the [[free electron model]], the electrons in a metal can be considered to form a Fermi gas. The number density <math>N/V</math> of conduction electrons in metals ranges between approximately 10<sup>28</sup> and 10<sup>29</sup> electrons/m<sup>3</sup>, which is also the typical density of atoms in ordinary solid matter. This number density produces a Fermi energy of the order of 2 to 10&nbsp;[[electronvolts]].<ref>{{Cite web |url=http://hyperphysics.phy-astr.gsu.edu/hbase/Tables/fermi.html |title=Fermi Energies, Fermi Temperatures, and Fermi Velocities |last=Nave |first=Rod |website=[[HyperPhysics]] |access-date=2018-03-21}}</ref>

===White dwarfs===
Stars known as [[white dwarfs]] have mass comparable to the [[Sun]], but have about a hundredth of its radius.  The high densities mean that the electrons are no longer bound to single nuclei and instead form a degenerate electron gas. Their Fermi energy is about 0.3&nbsp;MeV.

===Nucleus===
Another typical example is that of the [[nucleon]]s in the nucleus of an atom. The [[Nuclear size|radius of the nucleus]] admits deviations, so a typical value for the Fermi energy is usually given as 38&nbsp;[[MeV]].