1. What is the Power Equation?

The power equation \( P = \frac{V^2}{R} \) calculates the electrical power in watts (W) dissipated in a resistive component when the voltage (V) across it and its resistance (R) are known.

2. How Does the Calculator Work?

The calculator uses the power equation:

Where:

• \( P \) — Power in Watts (W)
• \( V \) — Voltage in Volts (V)
• \( R \) — Resistance in Ohms (Ω)

Explanation: The power dissipated in a resistor is proportional to the square of the voltage across it and inversely proportional to its resistance.

3. Importance of Power Calculation

Details: Calculating power is essential for designing electrical circuits, selecting appropriate components, and ensuring safe operation within power ratings.

4. Using the Calculator

Tips: Enter voltage in volts and resistance in ohms. Both values must be positive numbers. The calculator will compute the power in watts.

5. Frequently Asked Questions (FAQ)

Q1: Is this equation valid for AC circuits?
A: Yes, when using RMS values for AC voltage. The equation works for both AC and DC circuits.

Q2: What if I know current instead of voltage?
A: Use \( P = I^2 \times R \) where I is current, or \( P = V \times I \) if you know both voltage and current.

Q3: What are typical power ratings for resistors?
A: Common ratings include 1/8W, 1/4W, 1/2W, 1W, 5W, etc. Always use resistors rated for higher power than your calculation.

Q4: Does this account for power factor in AC circuits?
A: No, this simple equation assumes purely resistive loads. For reactive loads, power factor must be considered.

Q5: How accurate is this calculation?
A: It's theoretically precise for ideal resistors. Real-world factors like temperature coefficient may cause slight variations.