Which device is a semiconductor with three or more electrodes used for switching and amplification?

Which device is a semiconductor with three or more electrodes used for switching and amplification?

• A. Zener Diode
• B. Diode
• C. Regulator
• D. Transistor

Answer: (D)

A transistor is a semiconductor device with three or more terminals that can switch and amplify signals. It works by using a small current or voltage at the control terminal to regulate a larger current between the other two terminals, which enables both amplification and switching. This three-terminal arrangement (such as emitter, base, and collector in a BJT, or source, gate, and drain in a FET) is what allows it to control a larger load with a relatively small input signal. A diode, in contrast, is a two-terminal device and primarily provides a single-direction path for current, while a Zener diode is also two-terminal and used for voltage reference or clamping. A regulator focuses on maintaining a stable output voltage and, even when it has multiple pins, isn’t the general-purpose switching/amplifying element described. So the device that fits the description best is the transistor.

A transistor is a semiconductor device with three or more terminals that can switch and amplify signals. It works by using a small current or voltage at the control terminal to regulate a larger current between the other two terminals, which enables both amplification and switching. This three-terminal arrangement (such as emitter, base, and collector in a BJT, or source, gate, and drain in a FET) is what allows it to control a larger load with a relatively small input signal. A diode, in contrast, is a two-terminal device and primarily provides a single-direction path for current, while a Zener diode is also two-terminal and used for voltage reference or clamping. A regulator focuses on maintaining a stable output voltage and, even when it has multiple pins, isn’t the general-purpose switching/amplifying element described. So the device that fits the description best is the transistor.