International General Certificate of Secondary Education (IGCSE) Physics Practice Exam

Electrical power is defined as the rate at which electrical energy is transferred or converted. The correct definition can be derived from Ohm’s Law and the formulas related to electrical circuits. When calculating electrical power, one established equation is that power equals current multiplied by voltage, which is reflected in the choice labeled as B.

This relationship indicates that power (in watts) depends on both the flow of electric charge (current, measured in amperes) and the potential difference that drives the charge (voltage, measured in volts). Thus, when multiplying current by voltage, you obtain the power being consumed or produced in an electrical circuit.

The other definitions listed relate to specific aspects of electricity: energy per unit time describes power in a broader sense but lacks the specificity of the direct relationship between current and voltage. Voltage squared divided by resistance pertains to another form of power calculation derived from Ohm's Law but is not the primary definition. Resistance times current describes another relationship in ohmic materials but does not encompass the complete definition of electrical power.