The beta of a bipolar transistor is specified for what configurations?

Beta is the forward current gain of a bipolar junction transistor (BJT) when the base is used as the input terminal. This specific current gain parameter is applicable to the common emitter and common collector configurations, where the input current is the base current. In a common emitter configuration, beta relates the collector current to the base current as beta = Ic / Ib. In a common collector circuit (also known as an emitter follower), the overall current gain is 1 + beta, making beta the critical parameter for calculating current amplification in both setups. Common base configurations, by contrast, use the parameter alpha, which is the ratio of collector current to emitter current. Distractors mentioning a 'common gate' are incorrect because 'gate' is terminology used for Field Effect Transistors (FETs), not bipolar transistors.