*Question T6D08:
Which of the following is combined with an inductor to make a resonant circuit?*  

*Correct Answer is  D: Capacitor*  

### AI Response: (may contain errors)  

To create a resonant circuit, an inductor is combined with a capacitor. This combination allows the circuit to resonate at a specific frequency, known as the resonant frequency.

### Correct Answer: Capacitor
- **Why it's correct**: 
  - A resonant circuit, or LC circuit, consists of an inductor (L) and a capacitor (C). The resonance occurs when the inductive reactance ($X_L$) and capacitive reactance ($X_C$) are equal, allowing the circuit to oscillate at its natural frequency. The resonant frequency ($f_0$) can be calculated using the formula:
  
  $$
  f_0 = \frac{1}{2\pi\sqrt{LC}}
  $$
  
  where:
  - $L$ = inductance in henries
  - $C$ = capacitance in farads

### Why the Other Choices are Incorrect:
- **A: Resistor**  
  - A resistor does not store energy; it dissipates energy as heat. While resistors can be part of a circuit, they do not contribute to resonance.

- **B: Zener diode**  
  - A Zener diode is used for voltage regulation and does not participate in the energy storage needed for resonance. It is not a reactive component.

- **C: Potentiometer**  
  - A potentiometer is a variable resistor used to adjust voltage levels in a circuit. It does not provide the necessary reactive properties to create resonance.

### Summary:
- A resonant circuit requires both an inductor and a capacitor to function properly, allowing for energy storage and oscillation at a specific frequency. The other options do not fulfill this requirement.