Red wire is positive, black wire is negative. White stripe indicates negative wire, plain black wire is positive. DC power flows in one direction, common in batteries and electronics
Power (P) equals current (I) multiplied by voltage (V). At 120V, 1 amp consumes 120W, 2 amps consume 240W. At 240V, 1 amp consumes 240W, 2 amps consume 480W
Watts and volts are not independent but are related through the V x A = W formula. Volts represent potential difference between points with 1 ampere current. Watts measure power flow rate, similar to water flow through a hose
Watt (W) is SI unit of power equal to 1 joule per second. Named after James Watt, Scottish inventor who improved steam engine in 1776. Siemens proposed unit name in 1882, defining it as power through 1 ampere
Voltage is the difference in electric potential between two points. SI unit is volt (V), named after Alessandro Volta. Voltage can be caused by charge buildup or electromotive force. Voltage is a physical scalar quantity
Watts = volts × amps (W = V × A). Watts can be abbreviated as P (P = V × I). Amps can be abbreviated as I (I = A)