Which of these components can be used as an electronic switch?
The correct answer is C: Transistor. A transistor is the component that can be used as an electronic switch. Transistors can be controlled to switch between on (conducting) and off (non-conducting) states, making them ideal for electronic switching.
Transistors are semiconductor devices that can act as electronic switches. When a control signal (base current for bipolar, gate voltage for FET) is applied, the transistor switches on, allowing current to flow. When the control signal is removed, it switches off, blocking current. This switching capability makes transistors essential for amplifiers, digital circuits, power control, and many other applications. Transistors can switch much faster than mechanical switches and can be controlled by small signals.
Exam Tip
Transistor = Electronic switch. Remember: Transistors can be used as electronic switches - controlled by a small signal to switch larger currents on and off.
Memory Aid
"**T**ransistor = **E**lectronic **S**witch (think 'T = ES')"
Real-World Application
You're building a power control circuit. You use a transistor to switch a high-power load on and off. A small control signal to the transistor's base switches it on, allowing current to flow to the load. When you remove the control signal, the transistor switches off. This is how transistors work as electronic switches.
Key Concepts
Why Other Options Are Wrong
Option A: Incorrect. Varistors are voltage-dependent resistors used for surge protection. They don't function as electronic switches - they change resistance with voltage but don't switch on/off.
Option B: Incorrect. Potentiometers are variable resistors for adjusting resistance. They don't function as electronic switches - they're manual controls, not electronic switches.
Option D: Incorrect. Thermistors are temperature-dependent resistors. They change resistance with temperature but don't function as electronic switches.
题目解析
The correct answer is C: Transistor. A transistor is the component that can be used as an electronic switch. Transistors can be controlled to switch between on (conducting) and off (non-conducting) states, making them ideal for electronic switching. Transistors are semiconductor devices that can act as electronic switches. When a control signal (base current for bipolar, gate voltage for FET) is applied, the transistor switches on, allowing current to flow. When the control signal is removed, it switches off, blocking current. This switching capability makes transistors essential for amplifiers, digital circuits, power control, and many other applications. Transistors can switch much faster than mechanical switches and can be controlled by small signals.
考试技巧
Transistor = Electronic switch. Remember: Transistors can be used as electronic switches - controlled by a small signal to switch larger currents on and off.
记忆口诀
**T**ransistor = **E**lectronic **S**witch (think 'T = ES')
实际应用示例
You're building a power control circuit. You use a transistor to switch a high-power load on and off. A small control signal to the transistor's base switches it on, allowing current to flow to the load. When you remove the control signal, the transistor switches off. This is how transistors work as electronic switches.
错误选项分析
Option A: Incorrect. Varistors are voltage-dependent resistors used for surge protection. They don't function as electronic switches - they change resistance with voltage but don't switch on/off. Option B: Incorrect. Potentiometers are variable resistors for adjusting resistance. They don't function as electronic switches - they're manual controls, not electronic switches. Option D: Incorrect. Thermistors are temperature-dependent resistors. They change resistance with temperature but don't function as electronic switches.
知识点
Transistor, Electronic switch, Semiconductor device, Switching
Verified Content
Question from official FCC Technician Class question pool. Explanation reviewed by licensed amateur radio operators.