Definition
The unit of electrical power, equal to one joule of energy per second. In a direct current circuit, power in watts equals voltage multiplied by current (P = E × I).
Plain English
A measure of how much electrical work something does each second. The bigger the number, the more electricity it uses or produces.
Context Anchor
Seen in aircraft electrical system discussions, equipment power ratings, generator or alternator capacity, lighting, heaters, and maintenance checks.
Derivation
Named after James Watt, the 18th-century Scottish engineer who improved the steam engine. The unit was adopted to honor his work on measuring power, which is the rate of doing work.
Why Pilots Care
Aircraft electrical systems have limited generator and battery capacity; exceeding total wattage can cause overloads or failures in flight.
Analogy
Watts are like gallons per hour for electricity: they describe how fast energy is being used, not just how much is available.
Intuition Check
Watts are not the same as volts or amps. Volts describe electrical pressure, amps describe electrical flow, and watts describe the power being used or produced.
Example Sentence 1
The landing light is rated at 250 watts, so the technician verified the circuit could safely handle that load.
Example Sentence 2
Technicians add up the wattage of all installed equipment to confirm the alternator can supply the total load.