Final answer:
A watt is a unit of power, equivalent to one joule per second, used to measure the rate of energy consumption or output over time, as seen in devices like a 100-watt light bulb.
Step-by-step explanation:
A watt is a unit of power, which represents the rate at which energy is used or given off per unit of time. The formal definition of a watt is one joule per second (1 W = 1 J/s), highlighting its role in expressing how much energy is expended over a certain period. Notably, when we talk about common electrical devices such as light bulbs, we often refer to their energy consumption in watts; for example, a 100-watt bulb consumes 100 joules of energy every second. This measurement of power is applicable to numerous forms of energy and work, not just electricity. To express energy over time, watts are multiplied by time, giving us measurements such as kilowatt-hours (kWh), a common billing unit for electricity that is equivalent to the amount of electrical energy consumed.