*Question E8A03:
Which of the following describes a signal in the time domain?*  

*Correct Answer is  B: Amplitude at different times*  

### AI Response: (may contain errors)  

To understand the correct answer to the question about signals in the time domain, let's break down the options:

### Correct Answer: B - Amplitude at different times

- **Explanation**: A signal in the time domain represents how the amplitude of the signal varies over time. This means that if you were to plot the amplitude of the signal on the vertical axis and time on the horizontal axis, you would see how the signal's strength changes at each moment.

### Why the Other Choices are Incorrect:

- **A: Power at intervals of phase**  
  - **Explanation**: This option refers to power measurements related to phase, which is not a direct representation of a signal in the time domain. Power is typically analyzed in the frequency domain rather than the time domain.

- **C: Frequency at different times**  
  - **Explanation**: This describes a signal in the frequency domain, where you would analyze how the frequency content of a signal changes over time. It does not represent the amplitude variations that define a time-domain signal.

- **D: Discrete impulses in time order**  
  - **Explanation**: While this option describes a sequence of events in time, it does not capture the continuous nature of amplitude variations. Discrete impulses can be part of a time-domain signal, but they do not fully describe the general concept of amplitude over time.

### Summary

In summary, the time domain focuses on how the amplitude of a signal changes over time, which is best captured by option B. Understanding this distinction is crucial for analyzing and interpreting signals in various applications, including communications and signal processing.