*Question E5D05:
What parasitic characteristic causes electrolytic capacitors to be unsuitable for use at RF?*  

*Correct Answer is  C: Inductance*  

### AI Response: (may contain errors)  

Electrolytic capacitors are generally unsuitable for use at radio frequencies (RF) due to their parasitic inductance. Here's why:

1. **Correct Answer: Inductance**
   - Electrolytic capacitors have a significant amount of parasitic inductance due to their internal construction. This inductance can resonate with the capacitance at certain frequencies, causing the capacitor to behave unpredictably or even as an inductor at RF. This makes them unsuitable for RF applications where precise and stable capacitance is required.

2. **Why the Other Choices are Incorrect:**
   - **A: Skin effect**  
     Skin effect is a phenomenon where alternating current (AC) tends to flow near the surface of a conductor at high frequencies. While it affects conductors, it is not a primary concern for the operation of capacitors at RF.
   
   - **B: Shunt capacitance**  
     Shunt capacitance refers to unintended capacitance that can occur in circuits, but it is not a characteristic that makes electrolytic capacitors unsuitable for RF. In fact, capacitors are used to provide capacitance, so this is not a parasitic issue for them.
   
   - **D: Dielectric leakage**  
     Dielectric leakage refers to the small amount of current that leaks through the dielectric material of a capacitor. While this can affect the efficiency and performance of a capacitor, it is not the primary reason electrolytic capacitors are unsuitable for RF.

3. **Useful Rule of Thumb:**
   - At RF, components should have minimal parasitic inductance and capacitance to ensure predictable behavior. Electrolytic capacitors, with their high parasitic inductance, do not meet this requirement.

In summary, the parasitic inductance in electrolytic capacitors makes them unsuitable for RF applications, as it can lead to resonance and unpredictable behavior at high frequencies.