Which of the following displays an electrical quantity as a numeric value?
The correct answer is Meter. A meter (voltmeter, ammeter, ohmmeter, or multimeter) is an instrument that displays an electrical quantity as a numeric value. Meters measure voltage, current, resistance, or other electrical parameters and show the result as a number on a digital display or analog scale. For amateur radio operators, meters are essential tools for troubleshooting, testing equipment, measuring power supply voltages, checking circuit operation, and verifying component values. Digital multimeters are the most common type, displaying measurements as numeric values on an LCD screen. Understanding how to use meters is fundamental to electronics work and equipment maintenance.
Exam Tip
Meters display measurements as numbers. Think 'M'eter = 'M'easures and 'M'akes numbers visible. Potentiometers, transistors, and relays are components, not measuring instruments. If it shows numbers, it's a meter.
Memory Aid
"Meter = Measures and displays numbers. Think 'M'eter = 'M'easures and 'M'akes numbers visible. Shows voltage, current, or resistance as numeric values."
Real-World Application
When troubleshooting your power supply, you use a multimeter to measure the output voltage. The meter displays '13.8' on its screen, showing you the exact voltage. This numeric display tells you if the power supply is working correctly. Without a meter, you'd have no way to know the actual voltage value.
Key Concepts
Why Other Options Are Wrong
Option A (Potentiometer): Incorrect. A potentiometer is a variable resistor used to adjust resistance or create voltage dividers. It doesn't display measurements - it's a component you adjust, not a measuring instrument.
Option B (Transistor): Incorrect. A transistor is an active semiconductor component used for amplification or switching. It doesn't display anything - it processes signals.
Option D (Relay): Incorrect. A relay is an electrically-controlled switch. It doesn't display measurements - it switches circuits on or off.
题目解析
The correct answer is Meter. A meter (voltmeter, ammeter, ohmmeter, or multimeter) is an instrument that displays an electrical quantity as a numeric value. Meters measure voltage, current, resistance, or other electrical parameters and show the result as a number on a digital display or analog scale. For amateur radio operators, meters are essential tools for troubleshooting, testing equipment, measuring power supply voltages, checking circuit operation, and verifying component values. Digital multimeters are the most common type, displaying measurements as numeric values on an LCD screen. Understanding how to use meters is fundamental to electronics work and equipment maintenance.
考试技巧
Meters display measurements as numbers. Think 'M'eter = 'M'easures and 'M'akes numbers visible. Potentiometers, transistors, and relays are components, not measuring instruments. If it shows numbers, it's a meter.
记忆口诀
Meter = Measures and displays numbers. Think 'M'eter = 'M'easures and 'M'akes numbers visible. Shows voltage, current, or resistance as numeric values.
实际应用示例
When troubleshooting your power supply, you use a multimeter to measure the output voltage. The meter displays '13.8' on its screen, showing you the exact voltage. This numeric display tells you if the power supply is working correctly. Without a meter, you'd have no way to know the actual voltage value.
错误选项分析
Option A (Potentiometer): Incorrect. A potentiometer is a variable resistor used to adjust resistance or create voltage dividers. It doesn't display measurements - it's a component you adjust, not a measuring instrument. Option B (Transistor): Incorrect. A transistor is an active semiconductor component used for amplification or switching. It doesn't display anything - it processes signals. Option D (Relay): Incorrect. A relay is an electrically-controlled switch. It doesn't display measurements - it switches circuits on or off.
知识点
Meters, Measurement instruments, Multimeters, Electrical measurements
Verified Content
Question from official FCC Technician Class question pool. Explanation reviewed by licensed amateur radio operators.