*Question E5D10:
As a conductor’s diameter increases, what is the effect on its electrical length?*  

*Correct Answer is  D: It increases*  

### AI Response: (may contain errors)  

When considering the effect of a conductor's diameter on its electrical length, the correct answer is that the electrical length increases as the diameter increases.

### Explanation of the Correct Answer (D: It increases):
- **Electrical Length**: The electrical length of a conductor is related to its physical length and the speed of signal propagation through it. As the diameter of a conductor increases, the effective capacitance and inductance change, which can lead to a longer electrical length for a given physical length.
- **Skin Effect**: In AC applications, a thicker conductor reduces the skin effect, allowing more current to flow near the surface, which can effectively increase the conductor's electrical length.

### Why the Other Choices are Incorrect:
- **A: Thickness has no effect on electrical length**: This is incorrect because the diameter does affect the conductor's impedance and the distribution of current, which in turn influences the electrical length.
  
- **B: It varies randomly**: This choice is misleading. The relationship between diameter and electrical length is not random; it follows predictable electrical principles.
  
- **C: It decreases**: This is incorrect because increasing the diameter does not reduce the electrical length. Instead, it typically increases due to the reasons mentioned above.

### Useful Formulas and Rules of Thumb:
- **Electrical Length**: The electrical length can be approximated using the formula for the wavelength ($\lambda$) in a medium:
  
  $$\lambda = \frac{c}{f}$$

  where:
  - $c$ = speed of light in the medium (approximately $3 \times 10^8$ m/s in vacuum)
  - $f$ = frequency in hertz (Hz)

- **Impedance Consideration**: The impedance of a conductor is affected by its diameter. A thicker conductor has lower resistance and can support higher currents, which can influence the effective electrical length.

Understanding these concepts will help you grasp how conductor dimensions impact electrical properties, which is crucial for the Extra Class exam.