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DENJIRO: Take a look at these pictures here. If you look at the utility poles, you’ll see there are three electrical wires. Do you know why there are three wires?
GIRL: I wonder why.
DENJIRO: It’s strange if you think about it. Let’s perform an experiment to find out the reason. I’ve prepared a homemade generator. When the magnet in the middle spins, electricity is generated in the coils. Now, I’ve attached LED lights to each of the three coils. Let’s generate electricity in all three coils at once. The red and green LED lights are alternating. The electricity generated from the spinning magnet is an alternating current where it alternates between positive and negative. In order to turn the LED lights on, you need a wire for the electricity to get there and another for the electricity to return. Therefore, there are six wires. Now, let’s combine the three wires for returning electricity into one wire.
There are three wires for the electricity to get to the LED lights. The wires for returning electricity have been combined into one wire. Let me spin the magnet. We see that electricity is running even with only four wires. But the utility pole had three wires. Actually, you don’t need the wire for returning electricity. Let me remove it. Let me generate electricity.
GIRL: The lights turned on with just three wires!
NARRATOR: Why did the lights turn on with just three wires? Let’s explain using this setup where there is just one flashing LED instead of two.
DENJIRO: The three coils are spaced 120 degrees apart. The corresponding LED lights turn on in order according to the magnet’s spin. Electricity that went through the red wire and turned the LED light on returns through the other two wires. In the same fashion, electricity that traveled through the black and white wires returns through the other two wires. Therefore, it is possible to turn the lights on with just three wires.
This is why there are only three wires on a utility pole.
NARRATOR: This method allows for less wires and for electricity to be sent efficiently.
DENJIRO: I hope energy will bring you all happiness. Our magic word is "Happy Energy!"