Power is defined as what?

• A. The rate at which work is done or energy is transformed
• B. The amount of energy stored in a system
• C. The force causing motion
• D. The resistance of a circuit

Answer: (A)

Power is the rate at which energy is transferred or transformed. It measures how quickly work is done. If you lift a weight quickly, you transfer energy in a short time, so the power is high; if you lift it slowly, the power is lower. Mathematically, power equals work divided by time (P = W/t) and also equals the change in energy divided by time (P = ΔE/Δt). The unit is the watt, defined as one joule per second. This differs from energy stored, which is the total amount of energy present, not how fast it’s being used. It also differs from force alone—the force may cause movement and do work, but power is about the speed of energy transfer. In circuits, power can also be written as P = VI or P = I^2R, showing how energy transfer rate depends on voltage, current, and resistance.