Deep Dive: T7D01
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.
Why Other Answers 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.
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 Example
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.
Source & Coverage
Question Pool: 2022-2026 Question Pool
Subelement: T7D
Reference: 2022-2026 Question Pool · T7 - Practical circuits
Key Concepts
Verified Content
Question from the official FCC Technician Class pool. Explanation reviewed by licensed amateur radio operators and mapped to the T7D topic.