Which instrument would you use to measure electric potential?
The correct answer is B: A voltmeter. A voltmeter is used to measure electric potential (voltage). Voltage is the electrical potential difference between two points, measured in volts. Voltmeters are designed specifically for this purpose and can measure DC voltage, AC voltage, or both depending on the meter type. For amateur radio operators, voltmeters (often part of a multimeter) are essential tools for checking power supply voltages, troubleshooting circuits, measuring battery voltage, and verifying equipment operation. Understanding how to use a voltmeter is fundamental to electronics work.
Exam Tip
Voltmeter = measures voltage (electric potential). Think 'V'oltmeter = 'V'oltage measurement. Ammeters measure current, wavemeters measure frequency, ohmmeters measure resistance - none measure voltage.
Memory Aid
"Voltmeter = measures Voltage. Think 'V'oltmeter = 'V'oltage measurement. Measures electric potential difference between two points."
Real-World Application
You need to check if your power supply is outputting the correct 13.8 volts. You connect a voltmeter across the power supply output terminals. The voltmeter displays 13.8 volts, confirming the power supply is working correctly. Voltmeters are the standard tool for measuring voltage in any circuit.
Key Concepts
Why Other Options Are Wrong
Option A (Ammeter): Incorrect. An ammeter measures electric current (amperes), not voltage. Current and voltage are different electrical quantities.
Option C (Wavemeter): Incorrect. A wavemeter measures the wavelength or frequency of RF signals, not voltage. It's an RF measurement instrument.
Option D (Ohmmeter): Incorrect. An ohmmeter measures resistance (ohms), not voltage. Resistance and voltage are different measurements.
题目解析
The correct answer is B: A voltmeter. A voltmeter is used to measure electric potential (voltage). Voltage is the electrical potential difference between two points, measured in volts. Voltmeters are designed specifically for this purpose and can measure DC voltage, AC voltage, or both depending on the meter type. For amateur radio operators, voltmeters (often part of a multimeter) are essential tools for checking power supply voltages, troubleshooting circuits, measuring battery voltage, and verifying equipment operation. Understanding how to use a voltmeter is fundamental to electronics work.
考试技巧
Voltmeter = measures voltage (electric potential). Think 'V'oltmeter = 'V'oltage measurement. Ammeters measure current, wavemeters measure frequency, ohmmeters measure resistance - none measure voltage.
记忆口诀
Voltmeter = measures Voltage. Think 'V'oltmeter = 'V'oltage measurement. Measures electric potential difference between two points.
实际应用示例
You need to check if your power supply is outputting the correct 13.8 volts. You connect a voltmeter across the power supply output terminals. The voltmeter displays 13.8 volts, confirming the power supply is working correctly. Voltmeters are the standard tool for measuring voltage in any circuit.
错误选项分析
Option A (Ammeter): Incorrect. An ammeter measures electric current (amperes), not voltage. Current and voltage are different electrical quantities. Option C (Wavemeter): Incorrect. A wavemeter measures the wavelength or frequency of RF signals, not voltage. It's an RF measurement instrument. Option D (Ohmmeter): Incorrect. An ohmmeter measures resistance (ohms), not voltage. Resistance and voltage are different measurements.
知识点
Voltmeters, Voltage measurement, Electric potential, Test equipment
Verified Content
Question from official FCC Technician Class question pool. Explanation reviewed by licensed amateur radio operators.