1. What is the Power Formula?

The power formula \( P = \frac{V^2}{R} \) calculates the power dissipation in a resistor based on the voltage across it and its resistance. This is derived from Ohm's law and the basic power equation.

2. How Does the Calculator Work?

The calculator uses the power formula:

Where:

• \( P \) — Power (watts, W)
• \( V \) — Voltage (volts, V)
• \( R \) — Resistance (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 selecting appropriate resistors that can handle the generated heat without burning out, ensuring circuit reliability and safety.

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: Why is power proportional to voltage squared?
A: Because power is the product of voltage and current (P = V × I), and according to Ohm's law, current is proportional to voltage (I = V/R), resulting in P = V²/R.

Q2: What happens if I exceed a resistor's power rating?
A: The resistor will overheat, potentially causing it to burn out, change value, or even cause a fire hazard in extreme cases.

Q3: How do I choose the right resistor wattage?
A: Always select a resistor with a power rating at least 2-3 times higher than your calculated power dissipation for safety margin.

Q4: Can this formula be used for AC circuits?
A: For AC circuits with resistive loads, you can use RMS voltage values in the same formula to calculate average power.

Q5: What are common resistor power ratings?
A: Common ratings include 0.125W, 0.25W, 0.5W, 1W, 2W, 5W, and higher for power applications.