*Question T5A12:
What describes the number of times per second that an alternating current makes a complete cycle?*  

*Correct Answer is  D: Frequency*  

### AI Response: (may contain errors)  

The correct answer to the question is **D: Frequency**.

### Explanation of the Correct Answer:
- **Frequency** is defined as the number of complete cycles of an alternating current (AC) that occur in one second. It is measured in hertz (Hz), where 1 Hz equals 1 cycle per second. 

### Why the Other Choices are Incorrect:
- **A: Pulse rate**: This term typically refers to the number of pulses in a signal per second, which is not the same as the complete cycles of an AC waveform. Pulse rate is more relevant in digital signals rather than continuous AC signals.
  
- **B: Speed**: This term generally refers to the rate at which something moves or operates, but it does not specifically describe the cycles of an AC waveform. Speed is not a measure of frequency.
  
- **C: Wavelength**: Wavelength is the distance between successive peaks (or troughs) of a wave. It is related to frequency through the speed of the wave, but it does not describe how many cycles occur per second. The relationship is given by the formula:
  
  $$ 
  \text{Wavelength} = \frac{v}{f} 
  $$
  
  where:
  - $v$ = speed of the wave (in meters per second)
  - $f$ = frequency (in hertz)

### Summary:
- **Frequency** is the correct term for the number of cycles per second in an AC signal.
- The other options do not accurately describe this concept. 

Understanding these definitions will help you in both the exam and practical applications in amateur radio.