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Ohm's law: V = IR. Watt's law: P = VI = I²R = V²/R. For AC circuits, apparent power (VA) differs from real power (W) by the power factor (PF = cos φ). Enter any two of the four values and the others are solved. Used in circuit design, electrical troubleshooting, and understanding energy consumption of household appliances.
Enter any two of voltage (V), current (A), and resistance (Ω). The third is calculated. Power P = V × I.