Discovery Channel: Understanding Electricity

Everyone has to obey the laws of physics,

even if you're the King.

The power to make night into day,

create life or cause death,

this is all part of the mystery and magic of electricity.

Long before we knew what it was...

...long before we harnessed it...

...electricity was flowing through our bodies descended from the heavens.

So, there's constantly current flowing into the Earth from thunderstorms

and flowing out where there's not thunderstorms

and in that process an electric field

is generated in the atmosphere.

We walk around,

the voltage between your head and your toes when you walk around

is two or three hundred volts,

and nobody notices that because you grew up in it.

But, when there is enough of a voltage difference

between the clouds and the Earth,

it's hard not to notice.

One of those who was fascinated by the phenomenon was Benjamin Franklin.

Ben Franklin was a really smart guy.

He, he was one of the original experimenters

with electricity, period.

He, in fact, invented the designation

of positive and negative charge.

Today, high technology has replaced the kite.

In North Central Florida

scientists summon lightning and bring it to the Earth

with a rocket and a wire.

We can make the cloud produce lightning

and direct it where we want to direct it to do tests,

and that really hasn't been possible before.

They direct the lightning to strike simulated houses and power lines

to understand what happens when it hits.

The rocket launch provides a more controlled experiment

than anything Ben Franklin could have imagined.

Well, we do similar things.

He, he didn't think his kite was going to get struck,

and he thought that if it was going to get struck that

he wouldn't get hurt.

So, he was wrong there. If the kite had been struck,

he probably would have been killed, as have many people flying kites.

They load a rocket and launch it into the belly of a thundercloud.

From the rocket's tail, a spool of copper wire unwinds

creating a path for the lightning to follow.

There's a level of excitement and tension before you push the button,

and then there's a level of, of holding your breath for two seconds

when the rocket goes up

that's unlike anything else.

And, success feels real good because we, you know,

we only make it happen

...twenty, twenty-five times a summer,

so every one is a, is a big deal.

It's like a rocket-powered lightning rod.

Once the wire is shot up into

the air the lightning hits it.

In an instant, the electric current of the bolt moves down the wire

disintegrating it into a green vapor.

What flows down the lightning at fifty thousand amps

is the same thing that flows in your wall at ten amps.

The temperature of a lightning bolt

is more than fifty thousand degrees Fahrenheit,

six times hotter than the surface of the sun.

All that heat and light is generated by uncounted numbers of electrons

being forced to move.

An atom's nucleus has a positive charge.

Electrons orbiting the nucleus have a negative charge.

When electric current flows, electrons are torn from atoms

and move freely.

Electricity is the flow of electrical charge,

and most of the charge flows as, as electrons moving.

Whenever there's an oversupply of electrons an object develops

an overall negative charge.

Nature balances things out with equal positive charges somewhere else.

The potential difference between the charges is measured in volts.

Electric current, anything from static electricity to lightning bolts,

is electrons moving from negative to positive.

It seems like it's easier to make sparks and lightning

than not to make them.

Anytime you have two dissimilar materials rubbing together

you get sparks.

The path that leaping electrons follows depends on the material

they flow through.

The human body certainly will conduct current but not a lot,

not like a piece of copper.

Copper has a lot of loosely held electrons,

so it's a... good conductor.

The electrons of clay and rubber are too tightly bound to...

...their atoms to conduct electricity.

They're said to be insulators.

How electrons begin to move in the first place

is a result of a force of nature called electromagnetism.

Our whole technological civilization exists because electricity

can make magnetism.

And, magnetism can make electricity.

It goes back to the fact that we have

two kinds of forces that are present

that we call electricity or electromagnetism,

and those two forces are the electric force and the magnetic force.

The fundamental charges are a positive charge and a negative charge.

To see these forces at work,

head north and look up into the night sky.

Basically, the northern lights are the result of high energy electrical

currents from the sun

that are caught and guided by the Earth's magnetic field.

There's electricity out there.

Five, four, three, two, one.

And, we have lift-off of the Space Shuttle Columbia continuing space

research through the satellite of modern technology.

On February 25th, 1996, NASA and Italian researchers made a bold...

...attempt to harness the power in the atmosphere.

They generated electricity with a satellite and a wire.

It worked. Let's make sure we stay that way. Understand.

The mission was part of a new experiment of

tethering satellites in space.

The experiment was based on the simple principle

that when you move a conductor through a magnetic...

...field electrons start to flow.

This generates an electrical current that can flow through a circuit.

The satellite was thrust into space using small gas jets

and a thirteen mile long cable began to unreel.

And, if you put a, a wire inside of that tether you now have a moving wire

that moves across a magnetic field.

...That magnetic field, in this case, is the Earth's magnetic field,

and the motion is the motion of the Space Shuttle moving at very fast,

high velocities, orbital speeds.

The moving wire in the Earth's magnetic field generated

thirty-five hundred volts,

enough energy to power a space station.

Okay, we see the tension go way down but the tether's still going out fine,

very slight lateral oscillation.

The tether was clearly visible from the ground.

It was one of the biggest manmade objects ever sent into space.

For five hours the tether swept through our planet's magnetic field

generating more and more electricity.

How did they do?

The tether has broken, and it is going away from us.

Get on the, get it on the TV, please... get it on the TV.

The tether is broken.

Copy.

Trying to photograph it floating away from us.

Looking back, we quickly saw that, in fact, the tether had broken.

This was a very, you know, it's a big shock.

It's a, it's kind of an empty feeling in, in the pit of your stomach

when you look and you realize that there, there is the tether moving away

from us at about eighty feet per second,

and you just wanted to reach out and grab it.

The wire was generating so much electricity

that a sparkjumped from the wire to the satellite deployment system

and burned through the tether.

The four hundred, forty million dollar experimental satellite

just drifted away.

Yes, sir, well, those are some tether dynamics we did not want to see.

Well, look, we, we have demonstrated that you can generate

a lot of electricity with tether

and, unfortunately, we've also demonstrated that you can use tethers

to launch a satellite into a much higher orbit.

NASA will try the experiment again

because it could lead to a new, more reliable power system

for space stations

and help avoid situations like the mirror mishap.

We're moving, moving to actually is if we drive current in

the opposite direction in the tether and

if we could force the current to go the other way

it becomes a propulsive device,

so a propellantless spacecraft. And, the next generation of, of,

of space travelers may be using electric propulsion devices as opposed

to chemical propulsion devices,

a little Star Trek, if you will.

Perhaps, we notice electricity most when we don't have any.

On July 13th, 1977, New York City experienced a blackout.

For twenty-five hours, New Yorkers were without lights

or elevators or alarms.

Lightning had knocked out power lines north of the city,

and the utility company's backup equipment malfunctioned.

It takes a lot to

...keep the electricity working, not just in machinery, but in manpower

and it, it costs a lot of money to maintain these systems.

The utilities have to maintain their lines.

In the United States, 98 percent of homes and businesses

receive power from a vast electrical system

that is woven together with a web of power lines, a grid.

These power lines are naked live wires carrying half a million volts.

It's up to the linemen to inspect and repair every part of the grid,

usually without shutting down the power.

Yeah, Bill, I was going to start making a gradual left turn and

start heading over towards the line.

One of the most daring techniques is used on very high

voltage tension lines.

It's pretty dangerous I feel because you're mixing aviation

with, with electricity.

One, you're depending on the helicopter

everything mechanical to go right.

If it goes wrong, you're going to drop out of the sky like a rock.

If the lineman makes a mistake, you're going to vaporize.

These linemen and pilots work for Agrotors Incorporated.

One of the few companies that attempts these high wire acts,

Agrotors has the best safety record in the business.

It's dangerous work that only a handful of people in the world

are qualified to do.