Electrical & Circuits
6 min read
•Updated 2026-09-18
Ohm's Law and Electrical Power: Voltage, Current, Resistance & Wattage Formulas
A reference for Georg Ohm’s fundamental circuit law and Joule’s electrical power equations.
By AnyCalcHub Electrical Engineering Desk
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1. The Ohm's Law Triangle & Power Wheel
Ohm's law states that the electrical current flowing through a conductor between two points is directly proportional to the voltage across the two points and inversely proportional to the resistance.
Mathematical Formula
V = I × R; I = V / R; R = V / I Power (Watts): P = V × I = I² × R = V² / R
Step-by-Step Worked Example
Voltage (V)230 Volts
Current (I)10 Amperes
Step 1:Calculate Resistance: R = 230 / 10 = 23 Ω
Step 2:Calculate Electrical Power: P = 230 × 10 = 2,300 Watts (2.3 kW)
Final Result: Resistance: 23 Ω | Power: 2,300 W (2.3 kW)
Frequently Asked Questions
Common questions and mathematical nuances for this calculation.
What is the difference between AC and DC circuits in Ohm’s law?
In direct current (DC) circuits, resistance R represents total opposition to current. In alternating current (AC) circuits, inductive and capacitive reactance combine with resistance to form total impedance (Z).
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