Which terminal is described as the voltage input in the transistor definitions?

• A. Collector
• B. Base
• C. Emitter
• D. Gate

Answer: (A)

Voltage input means the terminal where the input signal is applied to control the device. In a field-effect transistor, the control signal is a voltage applied to the gate, which modulates the channel current; the gate is the input terminal. In a bipolar junction transistor, the input is the base, where a small current controls the larger current from collector to emitter. The collector is typically the output terminal, not the input. So, depending on the transistor type, the input is either the gate (for MOSFETs) or the base (for BJTs); among the given options, the term that describes the voltage input in common transistor definitions is the gate.