*Question T6C08:
What is component 9 in figure T-2?*  

*Correct Answer is  C: Variable resistor*  

### AI Response: (may contain errors)  

To determine what component 9 is in figure T-2, we need to understand the characteristics of each component type listed in the choices.

### Correct Answer: Variable Resistor

- A **variable resistor** (also known as a rheostat or potentiometer) is used to adjust resistance in a circuit. It typically has a sliding or rotating mechanism that changes the resistance value, allowing for control over current flow.

### Why the Other Choices are Incorrect:

- **A: Variable Capacitor**
  - A variable capacitor is used to change capacitance in a circuit, typically found in tuning circuits. It does not adjust resistance, so it cannot be component 9 if it is meant to control current flow.

- **B: Variable Inductor**
  - A variable inductor adjusts inductance in a circuit. Like the variable capacitor, it is not used for changing resistance, making it an incorrect choice for component 9.

- **D: Variable Transformer**
  - A variable transformer (or variac) adjusts voltage levels rather than resistance. It is used to control the output voltage in AC circuits, which does not align with the function of a variable resistor.

### Summary

- The correct answer is a **variable resistor** because it directly adjusts resistance in a circuit, which is likely the function of component 9 in figure T-2.
- The other options do not serve the same purpose and are therefore not applicable in this context.

### Useful Rule of Thumb

- Remember that variable components are typically used for tuning or adjusting specific parameters in a circuit:
  - **Variable Resistor**: Adjusts resistance.
  - **Variable Capacitor**: Adjusts capacitance.
  - **Variable Inductor**: Adjusts inductance.
  - **Variable Transformer**: Adjusts voltage. 

This understanding will help you identify components in similar questions on the exam.