1. What is a Resistor Power Rating Calculator?

Definition: This calculator determines the power dissipated by a resistor based on the voltage across it and its resistance.

Purpose: It helps electronics engineers and hobbyists select resistors with appropriate power ratings to prevent overheating and failure.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( P \) — Power dissipated (watts)
• \( V \) — Voltage across resistor (volts)
• \( R \) — Resistance (ohms)

Explanation: The voltage squared is divided by the resistance to calculate the power dissipation in watts.

3. Importance of Power Rating Calculation

Details: Proper power rating ensures resistors operate within safe limits, preventing overheating and potential circuit failure.

4. Using the Calculator

Tips: Enter the voltage across the resistor and its resistance. All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: Why is power rating important for resistors?
A: Exceeding a resistor's power rating can cause overheating, resistance change, or complete failure.

Q2: What's a typical power rating for common resistors?
A: Common through-hole resistors are typically 1/4W, 1/2W, or 1W. Surface mount resistors often range from 1/16W to 1W.

Q3: Should I select a resistor with higher power rating than calculated?
A: Yes, it's good practice to use a resistor rated for at least 2x the calculated power for safety margin.

Q4: Does this formula work for AC circuits?
A: Yes, but use RMS voltage values for AC circuits.

Q5: What happens if I exceed the power rating?
A: The resistor may overheat, change value, or fail completely, potentially damaging your circuit.