What describes the number of times per second that an alternating current makes a complete cycle?
The correct answer is D: Frequency. The term that describes the number of times per second that an alternating current makes a complete cycle is frequency. Frequency is measured in hertz (Hz), where 1 Hz = 1 cycle per second.
In an AC cycle, the current goes from zero, to maximum positive, back to zero, to maximum negative, and back to zero - that's one complete cycle. Frequency tells you how many of these complete cycles happen per second. For example, 60 Hz AC power completes 60 cycles per second. Higher frequency means more cycles per second. Frequency is fundamental to radio - radio signals are high-frequency AC currents, and the frequency determines which band you're operating on.
Exam Tip
Cycles per second = Frequency. Remember: Frequency (hertz) describes how many complete AC cycles occur per second. 1 Hz = 1 cycle per second.
Memory Aid
"**C**ycles **P**er **S**econd = **F**requency (think 'CPS = F' = Cycles Per Second = Frequency)"
Real-World Application
Your household AC power operates at 60 Hz. This means the current completes 60 full cycles every second - going from zero to positive maximum, back to zero, to negative maximum, and back to zero, 60 times per second. The frequency tells you how fast the AC is oscillating. In radio, frequencies are much higher - 146.52 MHz means 146,520,000 cycles per second.
FCC Part 97.3Key Concepts
Why Other Options Are Wrong
Option A: Incorrect. Pulse rate refers to pulses in digital signals, not the number of AC cycles per second.
Option B: Incorrect. Speed typically refers to velocity (distance per time), not the number of cycles per second.
Option C: Incorrect. Wavelength is the distance a wave travels in one cycle, not the number of cycles per second.
题目解析
The correct answer is D: Frequency. The term that describes the number of times per second that an alternating current makes a complete cycle is frequency. Frequency is measured in hertz (Hz), where 1 Hz = 1 cycle per second. In an AC cycle, the current goes from zero, to maximum positive, back to zero, to maximum negative, and back to zero - that's one complete cycle. Frequency tells you how many of these complete cycles happen per second. For example, 60 Hz AC power completes 60 cycles per second. Higher frequency means more cycles per second. Frequency is fundamental to radio - radio signals are high-frequency AC currents, and the frequency determines which band you're operating on.
考试技巧
Cycles per second = Frequency. Remember: Frequency (hertz) describes how many complete AC cycles occur per second. 1 Hz = 1 cycle per second.
记忆口诀
**C**ycles **P**er **S**econd = **F**requency (think 'CPS = F' = Cycles Per Second = Frequency)
实际应用示例
Your household AC power operates at 60 Hz. This means the current completes 60 full cycles every second - going from zero to positive maximum, back to zero, to negative maximum, and back to zero, 60 times per second. The frequency tells you how fast the AC is oscillating. In radio, frequencies are much higher - 146.52 MHz means 146,520,000 cycles per second.
错误选项分析
Option A: Incorrect. Pulse rate refers to pulses in digital signals, not the number of AC cycles per second. Option B: Incorrect. Speed typically refers to velocity (distance per time), not the number of cycles per second. Option C: Incorrect. Wavelength is the distance a wave travels in one cycle, not the number of cycles per second.
知识点
Frequency, AC cycles, Hertz, Cycles per second
Verified Content
Question from official FCC Technician Class question pool. Explanation reviewed by licensed amateur radio operators.