SPEED OF "ELECTRICITY"

How fast does electricity flow?

The quick answer

Inside the wires, the "something" moves very, very slowly, almost as slowly as the minute hand on a clock. Electric current is like a flow of syrup. Even maple syrup moves too fast, so that's not a good analogy. Electric charges flow as slowly as a river of warm putty. And in AC circuits, the moving charge doesn't move forward at all, instead it sits in one place and vibrates. Energy can flow fast in an electric circuit because metals are already filled with this "putty." If you push on one end of a column of putty, the far end moves almost instantly. Energy flows fast, yet an electric current is a very slow flow.

The complicated answer

Within all metals there is a substance which can move. This stuff has several different names: the Sea of Charge, or the Electron Sea, or the Electron Gas, or "charge." We often call it "electricity." Calling it "electricity" can be misleading because charge is not energy, yet many people think that electrical energy is the "electricity." It can be misleading because the Sea of Charge exists within in all metal objects, all the time, even when the metal has not been made into a wire and is not part of an electric device. If the Electron Sea is "electricity," then we must say that all metals are full of electricity. Better to call it by the name "charge-sea," and avoid the misleading word "electricity".

During an electric current, the wire stays still and the sea of charge flows along through it. When the flashlight switch is turned off and the lightbulb goes dark, the charge-sea stops moving forward. Even though it stops moving, the charge-sea is still inside of that wire. If the flashlight is again turned on and two light bulbs are connected in parallel instead of one, the electric current will have twice as large a value, and twice as much light will be created. And most important, the charge-sea of the battery's wires will flow twice as fast. In other words, THE SPEED OF THE CHARGES IS PROPORTIONAL TO THE VALUE OF ELECTRIC CURRENT; small current means low-speed charge flow, large current means high speed. Zero current means the charges have stopped. Note however that an electric current does not have just one speed. Charges speed up when they flow into a thinner wire. The high current in the lightbulb of a big flash-lantern will be much faster than the same current in the conductors in the lantern. Even though an electric current is a very slow flow of charges, we can't know the actual speed of flow unless first we know the *value* (the amperes) of the current in the wires.

If a thin wire is connected in a circuit end to end with a thick wire, it turns out that the charges in the thin wire move faster. This makes sense, it works just like water in rivers. If a huge wide river moves into a narrow channel, the water speeds up. When the channel opens out again downstream, the river slows down again. The flow in a very thin wire will be tend to be fast, even if the value of current is fairly low. This means that we can't know the speed of the flowing charge-sea unless we know how thick the wires are.

If a copper wire is connected into a series circuit with an aluminum wire of the same diameter, the charges in the copper will flow slower. This occurs because there is one movable charge per each atom in the metals, but there are more atoms packed into the copper than into the aluminum, so there is more charge in each bit of copper. When the charge-sea flows into the copper, it gets packed together and slows down. When it flows out into the aluminum, it spreads out a bit and speeds up. This means that we cannot know how fast the charges flow unless we know how dense the charge-sea is within the metal.