← All parts of this equation

Equation 26 · Part 1 · Every Crystal Has Its Own Speed of Light

Symbol v_F

vFv_F
vFv_F

What this part means

vFv_F is a part of this expression. Its role is fixed by the surrounding article and by the operations shown in the formula.

Its job in the formula

vFv_F is a part of this expression. Its role is fixed by the surrounding article and by the operations shown in the formula.

The passage around this formula

…is relativistic in form rather than merely in name. Near the point where graphene’s conduction and valence bands touch, its electrons obey a two-dimensional version of the massless Dirac equation, with the Fermi velocity vFv_F standing in for c . Mikhail Katsnelson, Konstantin Novoselov, and Andre Geim used that fact in 2006 to predict something the vacuum makes almost impossible to see: a chiral, massless particle hitting an electrostatic barrier head-on tunnels through with perfect transmission, regardless of the…

Read this part in the article →

Learn the underlying idea

A subscript is a label attached below a symbol. It often selects a time step, component, category, or member of a sequence.

Open the illustrated subscripts: which member of a family? guide →

See this notation across published equations →

Sources cited in the surrounding passage

These citations provide research context; check each source for the exact claim it supports.