What type of transistor has a gate, drain, and source?

• A. Bipolar junction transistor
• B. Field-effect transistor
• C. Darlington transistor
• D. Photo transistor

Answer: (B)

A field-effect transistor (FET) is characterized by its three terminals called the gate, drain, and source. The gate terminal regulates the flow of current between the drain and source terminals through an electric field, which is a defining trait of FETs. The voltage applied to the gate influences the conductivity of the channel, allowing control over the current flowing through the device.

In contrast, bipolar junction transistors (BJTs) have three terminals named the emitter, base, and collector. Darlington transistors consist of two BJTs connected together to provide high current gain, and they also have the same terminal configuration as BJTs. Photo transistors are special types of transistors that operate in response to light but do not change the terminal names of a typical BJT. Therefore, the presence of a gate, drain, and source makes the field-effect transistor the specific type of transistor being inquired about.