1. What is the Power Equation?

The power equation P = V²/R calculates the electrical power dissipated by a resistor when voltage and resistance are known. This fundamental formula is derived from Ohm's law and Joule's law of heating.

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 by 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 dissipation is crucial for selecting appropriate resistor wattage ratings, preventing overheating, ensuring circuit reliability, and designing efficient electronic systems.

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: What happens if power exceeds resistor rating?
A: The resistor will overheat, potentially causing failure, fire hazard, or circuit malfunction. Always use resistors with adequate power ratings.

Q2: Can this formula be used for AC circuits?
A: For AC circuits with resistive loads, use RMS voltage values. For reactive loads, additional calculations are needed.

Q3: What are common resistor power ratings?
A: Common ratings include 1/8W, 1/4W, 1/2W, 1W, 2W, 5W, and higher for power applications.

Q4: How does temperature affect power calculation?
A: Resistance changes with temperature, which can affect power dissipation. For precise applications, consider temperature coefficients.

Q5: Are there other power formulas?
A: Yes, P = V×I and P = I²×R are alternative forms. Choose based on available known values.