*Question T6A03:
What electrical parameter is controlled by a potentiometer?*  

*Correct Answer is  B: Resistance*  

### AI Response: (may contain errors)  

A potentiometer is a variable resistor that allows you to adjust the resistance in a circuit. 

1. **Why the correct answer is correct:**
   - A potentiometer consists of a resistive element and a movable contact (wiper). By turning the knob or sliding the control, you change the position of the wiper along the resistive element, which alters the resistance between the wiper and the terminals. This is why the correct answer is **B: Resistance**.

2. **Why the other choices are incorrect:**
   - **A: Inductance**: Inductance is a property of inductors, which store energy in a magnetic field. A potentiometer does not control inductance.
   - **C: Capacitance**: Capacitance is a property of capacitors, which store energy in an electric field. A potentiometer does not control capacitance.
   - **D: Field strength**: Field strength refers to the intensity of an electric or magnetic field. While a potentiometer can influence the voltage in a circuit, it does not directly control field strength.

3. **Useful formulas or rules of thumb:**
   - The resistance of a potentiometer can be calculated using Ohm's Law:
     $$V = I \times R$$
   - Where:
     - $V$ = voltage across the potentiometer
     - $I$ = current through the potentiometer
     - $R$ = resistance (which can be varied by the potentiometer)

This understanding of how a potentiometer works and its role in controlling resistance is essential for the Extra Class exam.