1. What is the Power Formula?

The power formula P = I² × R calculates the power dissipated in a resistor, where P is power in watts, I is current in amperes, and R is resistance in ohms. This is derived from Joule's law of heating.

2. How Does the Calculator Work?

The calculator uses the power formula:

Where:

• \( P \) — Power (Watts)
• \( I \) — Current (Amperes)
• \( R \) — Resistance (Ohms)

Explanation: The formula shows that power dissipation in a resistor is proportional to the square of the current flowing through it and directly proportional to its resistance.

3. Importance of Power Calculation

Details: Calculating power dissipation is crucial for circuit design, component selection, thermal management, and ensuring electrical safety in electronic systems.

4. Using the Calculator

Tips: Enter current in amperes and resistance in ohms. Both values must be positive numbers greater than zero for valid calculation.

5. Frequently Asked Questions (FAQ)

Q1: Why is power proportional to I²?
A: Power dissipation is proportional to I² because both voltage drop across the resistor (V = I×R) and current contribute to power (P = V×I = I²×R).

Q2: What happens if resistance is zero?
A: If resistance is zero, power dissipation would be zero regardless of current, as there would be no voltage drop and no energy conversion to heat.

Q3: Can this formula be used for AC circuits?
A: For AC circuits with purely resistive loads, this formula applies using RMS values of current. For reactive loads, additional factors must be considered.

Q4: How does temperature affect the calculation?
A: Resistance often changes with temperature, which means power dissipation calculations may need to account for temperature coefficients in precision applications.

Q5: What are typical power ratings for resistors?
A: Common resistor power ratings range from 0.125W to several watts, with higher power resistors used in applications requiring significant heat dissipation.