Ideal gas except for the specification of these constants. The results of the quantum Boltzmann gas are used in a number of cases including the Sackur–Tetrode equation for the entropy of an ideal gas and the Saha ionization equation for a weakly ionized plasma. The classical thermodynamic properties of an ideal gas can be described by two equations of state: The ideal gas law is the equation of state for an ideal gas, given by: where The ideal gas law is an extension of experimentally discovered gas laws. It can also be derived from microscopic considerations. Real fluids at low density and
Depletion region the bulk semiconductor, then a spontaneous depletion region forms if the gate is electrically shorted to the substrate, in much the same manner as described for the p–n junction above. The principle of charge neutrality says the sum of positive charges must equal the sum of negative charges: where "n" and "p" are the number of free electrons and holes, and formula_28 and formula_29 are the number of ionized donors and acceptors "per unit of length", respectively. In this way, both formula_28 and formula_29 can be viewed as doping spacial densities. If we assume full ionization and that formula_32, then: