1. What is the Power Formula?

The power formula P = I²R 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 known as Joule's first law.

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 selecting appropriate resistor wattage ratings, preventing overheating, and ensuring circuit reliability and safety.

4. Using the Calculator

Tips: Enter current in amperes and resistance in ohms. All values must be positive numbers. The calculator will compute the power dissipation in watts.

5. Frequently Asked Questions (FAQ)

Q1: Why is power proportional to I²?
A: Power dissipation increases with the square of current because both voltage drop across the resistor (V = IR) and current contribute to power (P = VI).

Q2: What happens if power exceeds resistor rating?
A: The resistor will overheat, potentially causing failure, circuit damage, or fire hazard. Always use resistors with appropriate power ratings.

Q3: Can this formula be used for AC circuits?
A: Yes, for resistive loads in AC circuits, use RMS values for current to calculate power dissipation.

Q4: How does temperature affect power calculation?
A: Resistance changes with temperature, which may affect actual power dissipation. The formula assumes constant resistance.

Q5: Are there other power formulas?
A: Yes, power can also be calculated as P = V²/R or P = VI, where V is voltage across the resistor.