Deep Dive: G5B09
The correct answer is B: 12 volts. The RMS voltage of a sine wave with a value of 17 volts peak is 12 volts. Vrms = Vpeak/√2 = 17/1.414 = 12.02V ≈ 12V. For amateur radio operators, this is a basic AC voltage calculation. Understanding this helps when working with AC voltages.
Why Other Answers Are Wrong
Option A (8.5 volts): Incorrect. 8.5 volts is half the peak (Vpeak/2), not RMS. RMS = Vpeak/√2, not Vpeak/2. Option C (24 volts): Incorrect. 24 volts is too high - that would be if RMS = peak, but RMS is less than peak. Calculation error. Option D (34 volts): Incorrect. 34 volts is 2× peak, not RMS. RMS is less than peak, not more.
Exam Tip
RMS from peak: Vrms = Vpeak/√2 = 17/1.414 = 12V. Think 'R'MS = 'R'eal 'M'easured = 'P'eak/√2. RMS voltage is peak divided by √2. Not peak/2 (8.5V), not peak (17V), not 2×peak (34V) - just peak/√2 (12V).
Memory Aid
RMS from peak: Vrms = Vpeak/√2 = 17/1.414 = 12V. Think 'R'MS = 'R'eal 'M'easured = 'P'eak/√2. RMS voltage is peak divided by √2. Standard AC voltage conversion.
Real-World Example
A sine wave has 17 volts peak. RMS voltage = 17/√2 = 17/1.414 = 12.02 volts ≈ 12 volts. RMS is the equivalent DC voltage for power calculations. This is the RMS voltage of a 17V peak sine wave.
Source & Coverage
Question Pool: 2023-2027 Question Pool
Subelement: G5B
Reference: 2023-2027 Question Pool · G5 - Electrical Principles
Key Concepts
Verified Content
Question from the official FCC General Class pool. Explanation reviewed by licensed amateur radio operators and mapped to the G5B topic.