watt

The watt is the SI unit of power, defined as one joule of work per second. The symbol is W. The unit is named after James Watt, an 18th‑century Scottish inventor whose improvements to the steam engine helped drive the Industrial Revolution.

Power is the rate at which energy is transferred or transformed. Thus, 1 W equals 1 J/s. In electrical contexts, power is often expressed as P = V × I for direct current, where V is voltage and I is current. In mechanical terms, power can be written as P = F × v, where F is force and v is velocity, or as P = τ × ω, where τ is torque and ω is angular velocity.

The watt is a derived unit in the International System of Units (SI). Energy is measured in joules, while power measures how quickly that energy is used or produced. A common related unit is the watt-hour (Wh), or kilowatt-hour (kWh), which is a unit of energy equal to the power of one kilowatt used for one hour. For electrical applications, devices are often rated in watts, kilowatts, or megawatts. A typical light bulb might be around 60 W, while electrical utilities report consumption in megawatts or gigawatts for large-scale generation.

In summary, the watt quantifies the rate of energy transfer, linking practical measurements of power to the underlying principles of physics.