What is a watt?

• A. The unit of electrical charge
• B. A device used to measure voltage
• C. The unit of electrical power
• D. A line used in power distribution

Answer: (C)

Power in an electrical system is how fast energy is being converted or consumed. The watt is the unit that expresses that rate. One watt equals one joule of energy transferred every second. In practical terms, you can multiply voltage by current to get power in watts (P = V × I) for DC or simple AC conditions. So a device drawing 0.5 A from a 120 V supply uses 60 W of power. This shows why watts are used to rate lighting and motors—it's about the rate of energy use, not the total energy or a measuring instrument. The other options aren’t correct because one is the unit of electrical charge (coulombs), another is a tool to measure voltage (a voltmeter), and another is a physical line that carries power (a conductor or transmission line).