*Question T5C02:
What is the unit of capacitance?*  

*Correct Answer is  A: The farad*  

### AI Response: (may contain errors)  

The correct answer is **A: The farad**.

1. **Why the correct answer is correct:**
   - The farad (F) is the standard unit of capacitance in the International System of Units (SI). Capacitance measures a capacitor's ability to store electrical charge. One farad is defined as the capacitance of a capacitor that stores one coulomb of charge at a potential difference of one volt:
   $$
   C = \frac{Q}{V}
   $$
   where:
   - $C$ = capacitance in farads
   - $Q$ = charge in coulombs
   - $V$ = voltage in volts

2. **Why the other choices are incorrect:**
   - **B: The ohm**: The ohm (Ω) is the unit of electrical resistance, not capacitance. It measures how much a material opposes the flow of electric current.
   - **C: The volt**: The volt (V) is the unit of electric potential or voltage. It indicates the potential difference that drives current through a circuit, but it does not measure capacitance.
   - **D: The henry**: The henry (H) is the unit of inductance. It measures a coil's ability to store energy in a magnetic field when current flows through it, which is unrelated to capacitance.

3. **Useful formulas or rules of thumb:**
   - The relationship between capacitance, charge, and voltage is crucial for understanding capacitors:
   $$
   C = \frac{Q}{V}
   $$
   - Capacitors in series and parallel configurations affect total capacitance:
     - For capacitors in series:
     $$
     \frac{1}{C_{total}} = \frac{1}{C_1} + \frac{1}{C_2} + \ldots
     $$
     - For capacitors in parallel:
     $$
     C_{total} = C_1 + C_2 + \ldots
     $$

Understanding these concepts will help you grasp the role of capacitance in circuits and prepare for the Extra Class exam.