*Question E4E08:
What current flows equally on all conductors of an unshielded multiconductor cable?*  

*Correct Answer is  B: Common-mode current*  

### AI Response: (may contain errors)  

The correct answer to the question is **B: Common-mode current**. 

### Explanation of the Correct Answer:
- **Common-mode current** refers to the current that flows in the same direction on all conductors of a multiconductor cable. This type of current can be caused by external electromagnetic interference or ground loops, and it affects all conductors equally. In unshielded multiconductor cables, common-mode currents can lead to unwanted noise and interference in the signals being transmitted.

### Why the Other Choices are Incorrect:
- **A: Differential-mode current**  
  - Differential-mode current flows in opposite directions on paired conductors. This is the desired mode for signal transmission in balanced lines, where the currents cancel out any external noise. Therefore, it does not flow equally on all conductors.

- **C: Reactive current only**  
  - Reactive current is associated with the storage of energy in inductors and capacitors and does not flow equally on all conductors. It is not a type of current that is defined by its equal flow across conductors.

- **D: Magnetically-coupled current only**  
  - Magnetically-coupled current refers to currents that are induced in conductors due to magnetic fields from nearby currents. This is not a standard term for currents that flow equally on all conductors and does not apply to the context of the question.

### Summary:
- Common-mode current flows equally on all conductors, making it the correct answer.
- Differential-mode current flows oppositely, while reactive and magnetically-coupled currents do not fit the description of equal flow across conductors.

Understanding these concepts is crucial for recognizing how different types of currents behave in multiconductor cables, especially in the context of interference and signal integrity.