1. What is the Power Formula?

The power formula P = V² / R calculates the power dissipation in a resistor based on the voltage across it and its resistance. This helps determine the appropriate wattage rating needed for a resistor to prevent overheating.

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 increases with the square of voltage and decreases with increasing resistance.

3. Importance of Power Rating Calculation

Details: Calculating the correct power rating is essential for selecting resistors that can safely handle the power dissipation without overheating or failing.

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 rating important for resistors?
A: Resistors with insufficient power rating can overheat, change value, or fail completely, potentially damaging the circuit.

Q2: What happens if I use a resistor with lower wattage than required?
A: The resistor may overheat, burn out, or cause a fire hazard in extreme cases.

Q3: Should I add a safety margin to the calculated power?
A: Yes, it's recommended to use a resistor with at least 2x the calculated power rating for safety and reliability.

Q4: Can this formula be used for AC circuits?
A: For AC circuits with resistive loads, use RMS voltage values in the calculation.

Q5: Are there other power formulas I should know?
A: Yes, P = I² × R (when current is known) and P = V × I (when both voltage and current are known).