In semiconductors, the Shockley diode equation—the relationship between the flow of electric current and the electrostatic potential across a p–n junction—depends on a characteristic voltage called the thermal voltage, denoted by .  The thermal voltage depends on absolute temperature  as
where  is the magnitude of the electrical charge on the electron with a value  Equivalently,
At room temperature ,  is approximately  which can be derived by plugging in the values as follows:
At the standard state temperature of , it is approximately . The thermal voltage is also important in plasmas and electrolyte solutions (e.g. the Nernst equation); in both cases it provides a measure of how much the spatial distribution of electrons or ions is affected by a boundary held at a fixed voltage.