ARRL Technician Practice Exam

Which of the following components can be made of three layers of semiconductor material?

1. Diode

2. Transistor

3. Capacitor

4. Inductor

The correct answer is: Transistor

A transistor is built from three layers of semiconductor material, making it a vital component in modern electronics. The three layers typically consist of two types of semiconductor material (p-type and n-type), which form either a p-n-p or n-p-n structure. This configuration allows the transistor to function as an amplifier or a switch, fulfilling essential roles in various circuits. The principle behind a transistor's operation is based on controlling the flow of current through the three layers, with the middle layer serving as the base that modulates the relationship between the input and output currents. This characteristic is fundamental to many electronic devices, from simple amplifiers to complex microprocessors. Other components mentioned do not share this three-layer structure. A diode, for instance, is constructed from only two layers of semiconductor material, which forms a p-n junction. Capacitors and inductors, on the other hand, are passive components and do not require semiconductor materials for their basic functionality. Therefore, the unique three-layer formation of transistors is crucial to their performance and purposes in electronic systems.