*Question T5A10:
Which term describes the rate at which electrical energy is used?*  

*Correct Answer is  C: Power*  

### AI Response: (may contain errors)  

The correct answer to the question is **C: Power**.

1. **Why the correct answer is correct:**
   - Power is defined as the rate at which electrical energy is used or converted. It is measured in watts (W) and can be calculated using the formula:
   $$
   P = V \times I
   $$
   where:
   - $P$ = power in watts
   - $V$ = voltage in volts
   - $I$ = current in amperes

2. **Why the other choices are incorrect:**
   - **A: Resistance**: This is a measure of how much a material opposes the flow of electric current, measured in ohms (Ω). It does not describe the rate of energy usage.
   - **B: Current**: This refers to the flow of electric charge, measured in amperes (A). While current is a component in calculating power, it does not itself represent the rate of energy usage.
   - **D: Voltage**: This is the electric potential difference between two points, measured in volts (V). Like current, it is a factor in the power calculation but does not indicate the rate of energy consumption.

3. **Useful formulas or rules of thumb:**
   - The relationship between power, voltage, and current can be summarized as:
   $$
   P = V \times I
   $$
   - Additionally, if you know the resistance ($R$) in a circuit, you can also express power as:
   $$
   P = I^2 \times R
   $$
   or
   $$
   P = \frac{V^2}{R}
   $$

These formulas help in understanding how power is calculated and its relationship with voltage and current in electrical circuits.