1. What is Electrical Power?

Electrical power is the rate at which electrical energy is transferred by an electric circuit. The SI unit of power is the watt (W), which is equal to one joule per second.

2. How Does the Power Formula Work?

The calculator uses the power formula:

Where:

• \( P \) — Power in watts (W)
• \( V \) — Voltage in volts (V)
• \( I \) — Current in amperes (A)
• \( PF \) — Power factor (unitless, 0 to 1)

Explanation: For DC circuits or AC circuits with purely resistive loads, the power factor is 1. For AC circuits with reactive components, the power factor is between 0 and 1.

3. Importance of Power Calculation

Details: Calculating power is essential for designing electrical systems, determining energy consumption, sizing components, and ensuring electrical safety.

4. Using the Calculator

Tips: Enter voltage in volts, current in amperes, and power factor (1 for DC or resistive AC circuits). All values must be valid (voltage > 0, current > 0, 0 ≤ PF ≤ 1).

5. Frequently Asked Questions (FAQ)

Q1: What's the difference between real power and apparent power?
A: Real power (P) is the actual power consumed, while apparent power (S = V×I) includes reactive power. The ratio P/S is the power factor.

Q2: When is power factor not equal to 1?
A: In AC circuits with inductive or capacitive loads (motors, transformers, etc.), where current and voltage are out of phase.

Q3: How does power relate to energy?
A: Energy is power multiplied by time (E = P×t). For example, 1 watt-hour is 1 watt of power for 1 hour.

Q4: What's a typical power factor for household appliances?
A: Resistive loads (heaters, incandescent lights) have PF=1. Motors might have PF=0.8-0.9. Electronics with switching power supplies often have poor PF (0.5-0.7).

Q5: Why is power factor correction important?
A: Low power factor means higher current is needed for the same real power, increasing energy losses in distribution systems.