*Question E5D07:
What combines to create the self-resonance of a component?*  

*Correct Answer is  B: The component’s nominal and parasitic reactance*  

### AI Response: (may contain errors)  

To understand the self-resonance of a component, we need to consider how components behave at different frequencies.

### Correct Answer: B: The component’s nominal and parasitic reactance

1. **Explanation:**
   - **Nominal Reactance:** This is the intended reactance of the component, such as the inductive reactance of an inductor or the capacitive reactance of a capacitor.
   - **Parasitic Reactance:** These are unintended reactances that occur due to the physical construction of the component. For example, an inductor may have some parasitic capacitance between its windings.
   - **Self-Resonance:** Occurs when the nominal reactance and the parasitic reactance cancel each other out, typically at a specific frequency. At this frequency, the component behaves like a pure resistor.

### Why Other Choices Are Incorrect:

- **A: The component’s resistance and reactance**
  - Resistance does not directly contribute to self-resonance. Self-resonance is about the balance between inductive and capacitive reactance, not resistance.

- **C: The component’s inductance and capacitance**
  - While inductance and capacitance are involved, the key factor is the interaction between the nominal and parasitic reactances, not just the inductance and capacitance themselves.

- **D: The component’s electrical length and impedance**
  - Electrical length and impedance are more relevant to transmission lines and antennas, not the self-resonance of individual components.

### Useful Formula:

The self-resonant frequency ($f_0$) of a component can be approximated by the formula:

$$
f_0 = \frac{1}{2\pi\sqrt{LC}}
$$

where:
- $L$ is the inductance (including parasitic inductance)
- $C$ is the capacitance (including parasitic capacitance)

This formula shows how the self-resonant frequency is determined by the interplay of inductance and capacitance, including their parasitic components.