Electrical energy can be defined as the energy caused by the movement of electrons from one point to another. The amount of electrical energy can be determined by the power used by a device over a specific time interval. The SI unit of electrical energy is the joule, or watt-second, whereas the commercial unit is the kilowatt-hour, also known as the Board of Trade unit. Consider a 60 Watt incandescent bulb and a 20 Watt LED bulb, each producing an equivalent amount of light. Determine the cost savings in replacing the incandescent bulb with the LED bulb running for 4 hours daily for 365 days, assuming 12 cents per kilowatt-hour is the average energy rate charged by the power company. First, individually determine the amount of electrical energy consumed by the incandescent bulb and the LED bulb. Second, multiply the energy consumed by the individual bulb by the cost charged by the power company. The LED bulb uses three times less energy and saves about $7.00 compared to the incandescent bulb.