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Joule's Law Formula:
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Power dissipation refers to the process where electrical energy is converted to heat energy in a resistor or circuit component. This phenomenon is described by Joule's Law, which states that the power dissipated in a resistor is proportional to the square of the current flowing through it and its resistance.
The calculator uses Joule's Law formula:
Where:
Explanation: The formula shows that power dissipation increases with the square of current, meaning small increases in current can lead to significant increases in heat generation.
Details: Calculating power dissipation is crucial for circuit design to prevent component overheating, ensure proper heat sinking, select appropriate resistor wattage ratings, and maintain circuit reliability and safety.
Tips: Enter current in amperes and resistance in ohms. Both values must be positive numbers. The calculator will compute the power dissipation in watts.
Q1: Why does power increase with the square of current?
A: Because both voltage drop across the resistor (V = I × R) and current contribute to power (P = V × I), resulting in P = I² × R.
Q2: What happens if power dissipation exceeds rating?
A: Components may overheat, leading to failure, reduced lifespan, or in extreme cases, fire hazard. Always use components rated for expected power dissipation.
Q3: Can this formula be used for AC circuits?
A: Yes, for resistive loads in AC circuits, use RMS values for current to calculate average power dissipation.
Q4: How does temperature affect resistance?
A: For most resistors, resistance increases with temperature, which can affect power calculations in real-world applications.
Q5: What are typical power ratings for resistors?
A: Common ratings include 1/8W, 1/4W, 1/2W, 1W, 2W, 5W, and higher for power applications.