*Question G9A05:
How does the attenuation of coaxial cable change with increasing frequency?*  

*Correct Answer is  B: Attenuation increases*  

### AI Response: (may contain errors)  

As frequency increases, the attenuation of coaxial cable also increases. This is due to several factors, including skin effect and dielectric losses, which become more pronounced at higher frequencies.

1. **Why the correct answer is correct (B: Attenuation increases):**
   - **Skin Effect:** At higher frequencies, the current tends to flow more on the surface of the conductor rather than through its entire cross-section. This reduces the effective area for current flow, increasing resistance and thus attenuation.
   - **Dielectric Losses:** The dielectric material in the coaxial cable also absorbs more energy at higher frequencies, contributing to increased attenuation.

2. **Why the other choices are incorrect:**
   - **A: Attenuation is independent of frequency:** This is incorrect because attenuation is indeed dependent on frequency, as explained above.
   - **C: Attenuation decreases:** This is incorrect because the physical phenomena involved (skin effect and dielectric losses) cause attenuation to increase, not decrease, with frequency.
   - **D: Attenuation follows Marconi’s Law of Attenuation:** There is no such law. This choice is incorrect and likely included to mislead.

3. **Useful formulas or rules of thumb:**
   - A general rule of thumb is that attenuation in coaxial cables increases approximately with the square root of frequency. This can be expressed as:
     $$ \text{Attenuation} \propto \sqrt{f} $$
   - This means that if you double the frequency, the attenuation will increase by a factor of about $\sqrt{2}$, assuming other factors remain constant.

Understanding these principles will help you anticipate how coaxial cable performance changes with frequency, which is crucial for designing and maintaining effective communication systems.