Some problems about "electric power calculation" I always confuse P = UI and P = u ^ 2 / R when solving the calculation of electric power I don't know which formula to use Please master advice: under what circumstances. With P = UI calculation Under what circumstances is p = u ^ 2 / r used to calculate ``` Add. These seem to relate to what the actual power rating is.

For a circuit, u = IR only exists when the consumer is pure resistance (that is, when all electric energy is used for heating), so p = UI is applicable to any circuit, and P = u ^ 2 / R is only applicable to pure resistance circuit

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