Which quantity is defined as work per unit time and is measured in watts?

• A. Power
• B. Voltage
• C. Current
• D. Resistance

Answer: (A)

Power is the rate at which work is done or energy is transferred. It tells you how quickly energy is used or delivered, and in electrical contexts it is measured in watts. One watt equals one joule of energy transferred every second, so the quantity defined as work per unit time and measured in watts is power. Voltage is electric potential difference, current is the flow of electric charges, and resistance is opposition to current; their units are volts, amperes, and ohms, respectively. When voltage and current are known, power can be found with P = V × I, linking the concept directly to how fast energy moves through a circuit.