Figure 1-28.Obtaining gain and transconductance.
As you can see, mu is a measure of the ability of a tube to amplify. By comparing the mu of two
different types of tubes, you can get an idea of their efficiency. For example, assume you have two
different tubes, one with a mu of 50, and the other with a mu of 100. If you place each tube in a circuit
whose input varies by 2 volts, you can expect the following changes in plate voltage.