1. What is the Power Formula?

The power formula P = V² / R calculates the electrical power (in watts) dissipated in a resistor when the voltage across it and its resistance are known. This is derived from Joule's law of heating.

2. How Does the Calculator Work?

The calculator uses the power formula:

Where:

• \( P \) — Power in watts (W)
• \( V \) — Voltage in volts (V)
• \( R \) — Resistance in ohms (Ω)

Explanation: The formula shows that power is proportional to the square of the voltage and inversely proportional to the resistance.

3. Importance of Power Calculation

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

4. Using the Calculator

Tips: Enter voltage in volts and resistance in ohms. All values must be valid (voltage > 0, resistance > 0).

5. Frequently Asked Questions (FAQ)

Q1: What happens if resistance is zero?
A: Resistance cannot be zero in practical circuits as it would result in infinite current and power, which is physically impossible.

Q2: Can this formula be used for AC circuits?
A: For AC circuits with resistive loads, the formula works with RMS voltage values. For reactive loads, additional factors need to be considered.

Q3: What are typical power ratings for resistors?
A: Common power ratings include 0.125W, 0.25W, 0.5W, 1W, 2W, 5W, and higher for specialized applications.

Q4: How does temperature affect power calculation?
A: Resistance values often change with temperature, which may affect power calculations in real-world applications.

Q5: What safety considerations are important?
A: Always ensure components are operated within their specified power ratings to prevent overheating and potential failure.