What is the formula for calculating power in an electric circuit?
GeneralClass 12AllAnswered 27 Mar 2026
Answer
There are three main formulas for electrical power, all interconnected through Ohm's Law:
- P = V × I (Power = Voltage × Current)
- P = I² × R (Power = Current² × Resistance)
- P = V² / R (Power = Voltage² / Resistance)
When to use each:
- Use P = V × I when you know both voltage and current
- Use P = I² × R when you know current and resistance
- Use P = V² / R when you know voltage and resistance
Example: A circuit with 12V and 2A flowing through it: P = 12 × 2 = 24 watts
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