Power (electrical) Calculator
Calculate electrical power from current and voltage.
Formula first
Overview
Electrical power represents the rate at which energy is transferred or transformed within an electric circuit. It is defined as the product of the potential difference across a conductor and the current flowing through it, typically measured in Watts.
Symbols
Variables
I = Current, V = Voltage, P = Power
Apply it well
When To Use
When to use: This formula is the primary method for calculating power in direct current (DC) circuits or resistive alternating current (AC) loads. Use it whenever you need to relate the energy consumption rate to the voltage drop and current flow of a specific component.
Why it matters: Calculating power is crucial for sizing electrical components like fuses and wires to prevent overheating or fire. It also allows consumers and engineers to determine the energy efficiency and operating costs of electronic devices and machinery.
Avoid these traps
Common Mistakes
- Using mA without converting to A.
- Confusing power with energy.
One free problem
Practice Problem
A portable electric heater is plugged into a 240V outlet and draws a current of 5A. Calculate the total power output of the heater.
Solve for:
Hint: Multiply the voltage by the current to find the power in Watts.
The full worked solution stays in the interactive walkthrough.
References
Sources
- Halliday, Resnick, Walker, Fundamentals of Physics
- Wikipedia: Electric power
- NIST Special Publication 330: The International System of Units (SI)
- Fundamentals of Physics by Halliday, Resnick, and Walker
- Electrical power (Wikipedia article)
- Halliday, Resnick, Walker, Fundamentals of Physics, 10th Edition
- IUPAC Gold Book, 'electric power'
- Britannica, 'Electric power'