How fast does an electron move down a wire?
Which would win in a race, an electron or
a snail?
Let's answer the second question first.
You may be surprised to learn that the snail
would win, easily.
Let's use this electrical circuit as a
racetrack. It has an on/off switch,
a battery, and a light. The distance around
our racetrack is 22 inches.
According to the 1999
World Almanac and Book a Facts,
a garden snail can move it a whopping
0.03 miles per hour.
That's 0.528 inches per
second. We'll call her Joan.
The 1998 Guiness Book of
World Records says that a garden snail named
Archie went a whopping 13 inches
in 3 minutes.
That's 0.108 inches per
second. This is Archie.
And here's our electron. We'll talk about
how fast it moves later.
And they're off! Archie and Joan roar ahead
with the electron...
... well it's moving but it doesn't look
like it yet.
Joan's in the lead and Joan zooms ahead
with Archie behind. And the electron...
... well this will take all day so let's fast
forward it.
And the winner is Joan, with Archie well
behind. But our electron has moved a mere
one-tenth of an inch.
But doesn't electricity move at the
speed of light?
The speed of light is around 300,000
kilometers per second or
186,000 miles
per second. Actually, in an unshielded copper
wire like this one, electricity moves at
around 96% the speed of
light, so 178,560 miles per 
second.
At that speed, ignoring other losses,
electricity could circle the globe over
seven times is just one second. So
electricity moves at close to the speed of light.
But the electrons don't, as we saw with our
little racetrack. One way to visualize
what's going on is to use this row of marbles. When we
push on one marble, the effect of that push is
passed on from marble to marble and the result
is felt by the wooden tile almost
immediately.
The individual marbles represent individual
electrons.
They don't move very far on the way.
Electricity is represented by the effect on
the wooden tile. That effect is passed on
almost immediately.
And to answer our other question, how fast
are the electrons moving?
The electrons move at a velocity called the
drift velocity. Here's one easy 
formula we can use to find out. Calculating 
it out we get 0.0007 
meters per second or
0.0028 inches per
second. Remember, our slowest snail, Archie, goes
0.108 inches per second,
38 times as fast as the electron.
For the electron to go around our 22
inch long track it would take
7,857 
seconds, or around 131
minutes, ignoring the time spent in the
battery, switch and light.
Electricity from a battery is direct current
electricity. The electrons go around in
one direction.
Electricity you get from your wall socket
is alternating current electricity.
The electrons go one way, stop, go back the
other way, stop, and go the other way again.
Even here, though, the electrons are moving
slow, like we've been talking about.
Even though the effect, electricity, moves
very fast.
So if you're betting person, bet on the
snails to win, not the electrons.
Well, thanks for watching! Check out my youtube
channel, rimstarorg, for more fun
videos like this.
That includes one on how radiation works.
How to make a solar cell using a copper
sheet.
And one explaining all sorts of things
about fresnel lenses.
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