|MLA Citation:||Bloomfield, Louis A. "Question 1190"|
How Everything Works 18 Jan 2018. 18 Jan 2018 <http://howeverythingworks.org/print1.php?QNum=1190>.
To understand how this difference in speeds is possible, think about what happens when you turn on the water to a long hose. If that hose is already filled with water, water will immediately begin pouring out of the hose's end even though the water is flowing quite slowly through the hose. While the water itself moves slowly, the water's effects travel through the hose at the speed of sound in water—several miles per second! Water at the end of the hose "knows" that you have opened the faucet long before new water from the faucet arrives.
Similarly, when you turn on a flashlight, electrons begin to flow out of the battery's negative terminal at speeds of only a few millimeters per second. But these electrons don't have to travel all the way to the light bulb for the bulb to light up. When these electrons leave the battery, they push on the electrons in front of them, which push on the electrons in front of them, and so on. They produce an electromagnetic wave that rushes through the wire at an incredible speed. As a result, electrons begin flowing through the light bulb only a few billionths of a second after the first electron left the battery. So while the electrons that carry electricity through the power grid flow rather slowly, the power they deliver moves remarkably fast.