*Question E5D12:
What is reactive power?*  

*Correct Answer is  D: Wattless, nonproductive power*  

### AI Response: (may contain errors)  

Reactive power is an important concept in AC circuits, particularly in systems that include inductors and capacitors. 

### Correct Answer: D - Wattless, nonproductive power

- **Explanation**: Reactive power is measured in volt-amperes reactive (VAR) and represents the power that oscillates between the source and reactive components (inductors and capacitors) in the circuit. It does not perform any real work (like lighting a bulb or turning a motor) but is necessary for maintaining the electric and magnetic fields in these components. Hence, it is often referred to as "wattless" or "nonproductive" power.

### Why the Other Choices are Incorrect:

- **A: Power consumed in circuit Q**  
  - This choice is vague and does not accurately describe reactive power. Reactive power is not simply "consumed" but rather oscillates back and forth in the circuit.

- **B: Power consumed by an inductor’s wire resistance**  
  - This refers to real power (measured in watts), which is the power actually consumed by the resistance in the inductor. Reactive power does not involve energy loss due to resistance.

- **C: The power consumed in inductors and capacitors**  
  - This statement is misleading. While inductors and capacitors do store and release energy, they do not consume power in the same way resistive loads do. Reactive power is not "consumed" but rather exchanged between the source and the reactive components.

### Useful Formulas:

- **Real Power (P)**:  
  $$P = V \times I \times \cos(\phi)$$  
  where $\phi$ is the phase angle between voltage and current.

- **Reactive Power (Q)**:  
  $$Q = V \times I \times \sin(\phi)$$  

- **Apparent Power (S)**:  
  $$S = V \times I$$  
  where $S$ is measured in volt-amperes (VA) and is the vector sum of real and reactive power.

### Summary:
Reactive power is essential for the operation of AC circuits with inductors and capacitors, but it does not perform any useful work. Understanding this concept is crucial for managing power systems effectively.