Charge is not the same as useful energy Silent captioned film. Concept artwork, not experimental footage. 00–07 seconds: EXPLAINER / 01 Charge is a quantity. Power is a rate. Q = ∫ I dt P = V × I A voltage reading alone does not establish delivered power. 07–14 seconds: EXPLAINER / 02 Follow the same load. Follow the same time. Measure voltage and current simultaneously at a defined load. Do not multiply separate open-circuit and short-circuit readings. 14–21 seconds: EXPLAINER / 03 Useful energy is measured over time. E = ∫ V I dt Report the interval, missing samples, uncertainty and supplied resources.