*Question G6A11:
What happens when an inductor is operated above its self-resonant frequency?*  

*Correct Answer is  C: It becomes capacitive*  

### AI Response: (may contain errors)  

When an inductor is operated above its self-resonant frequency, it behaves differently than it does at lower frequencies. Here's why the correct answer is that it becomes capacitive:

1. **Correct Answer: It becomes capacitive**
   - An inductor has both inductance and parasitic capacitance. At its self-resonant frequency, the inductive reactance ($X_L$) and the capacitive reactance ($X_C$) are equal, and they cancel each other out. Above this frequency, the capacitive reactance dominates, causing the inductor to behave like a capacitor.

2. **Why the other choices are incorrect:**
   - **A: Its reactance increases**  
     - This is incorrect because, above the self-resonant frequency, the inductive reactance does not increase. Instead, the inductor's behavior shifts to capacitive, and the overall reactance decreases.
   
   - **B: Harmonics are generated**  
     - While harmonics can be a concern in some circuits, the primary effect of operating an inductor above its self-resonant frequency is the change in its reactive behavior, not harmonic generation.
   
   - **D: Catastrophic failure is likely**  
     - Operating an inductor above its self-resonant frequency does not inherently lead to catastrophic failure. The main issue is the change in its reactive properties, not physical damage.

3. **Useful Formulas:**
   - The self-resonant frequency ($f_0$) of an inductor can be found using:  
     $$ f_0 = \frac{1}{2\pi\sqrt{LC}} $$
     where $L$ is the inductance and $C$ is the parasitic capacitance.
   - Below $f_0$, the inductor behaves inductively. Above $f_0$, it behaves capacitively.

Understanding these concepts helps in analyzing circuits where inductors are used, especially in RF applications.