Deep Dive: G7A07
The correct answer is A: A series of DC pulses at twice the frequency of the AC input. The output waveform of an unfiltered full-wave rectifier connected to a resistive load is a series of DC pulses at twice the frequency of the AC input. Full-wave rectification produces pulses at 120 Hz (for 60 Hz input) or 100 Hz (for 50 Hz input). For amateur radio operators, this explains unfiltered rectifier output. Understanding this helps when analyzing power supplies.
Why Other Answers Are Wrong
Option B: Incorrect. Pulses aren't at the same frequency as AC input - full-wave produces pulses at twice the input frequency. Same frequency would be half-wave. Option C: Incorrect. Output isn't a sine wave at half frequency - it's DC pulses, not a sine wave, and at twice frequency, not half. Sine wave and half frequency are both wrong. Option D: Incorrect. Output isn't steady DC voltage - unfiltered output has pulses/ripple, not steady DC. Steady DC requires filtering.
Exam Tip
Unfiltered full-wave output = DC pulses at twice AC frequency. Think 'F'ull-'W'ave = 'F'ull cycle rectified = 'T'wice frequency pulses. Full-wave produces DC pulses at twice the AC input frequency. Not same frequency, not sine wave, not steady DC - just pulses at 2× frequency.
Memory Aid
Unfiltered full-wave output = DC pulses at twice AC frequency. Think 'F'ull-'W'ave = 'T'wice frequency pulses. Full-wave produces DC pulses at twice the AC input frequency. Filtering needed for steady DC.
Real-World Example
An unfiltered full-wave rectifier with 60 Hz AC input produces DC pulses at 120 Hz (twice the frequency). The output is a series of positive DC pulses, not steady DC. Filtering (capacitors/inductors) is needed to smooth this into steady DC. This is why filters are essential in power supplies.
Source & Coverage
Question Pool: 2023-2027 Question Pool
Subelement: G7A
Reference: 2023-2027 Question Pool · G7 - Practical Circuits
Key Concepts
Verified Content
Question from the official FCC General Class pool. Explanation reviewed by licensed amateur radio operators and mapped to the G7A topic.