Figure 6 shows the small-signal circuit of Figure 5 with the input short-circuited and a test current placed at its output. The output resistance is found using this circuit as:  Using Ohm's law, various currents have been found, as indicated on the diagram. Collecting the terms for the base current, the base current is found as: where formula_11 is defined above. Using this value for base current, Ohm's law provides formula_26 as: Substituting for the base current, and collecting terms, where || denotes a parallel connection and formula_29 is defined above. Because formula_29 generally is a small resistance when the current gain formula_20 is large, formula_29 dominates the output impedance which therefore also is small. A small output impedance means the series combination of the original voltage source and the voltage follower presents a Thévenin voltage source with a lower Thévenin resistance at its output node; that is, the combination of voltage source with voltage follower makes a more ideal voltage source than the original one.