War of the currents
NEW ULM — It was all about AC versus DC Tuesday at Jefferson Elementary, though it had nothing to do with rock and roll.
Bakken Museum employees Siri Hellerman, school proposal outreach coordinator, and Nathan Meyer, invention programs coordinator, presented about the basics of how electricity is generated, the difference between alternating current (AC) and direct current (DC) and the schism between inventors Thomas Edison and Nikola Tesla.
The two presenters explained that electricity comes from the movement of electrons down a path, or circuit.
“That is what we call the flow, or the current, of electricity, but you know this does not happen magically,” Hellerman said. “To get our electrons flowing, there is actually a recipe and there are three ingredients.”
Those ingredients are: magnets, wire and movement. At its base, electrical generation is moving a wheel of magnets in a circle of copper wire.
The presenters explained that often coal, oil or natural gas are burned to boil water which produces the steam that can turn the wheel of magnets.
Other ways to generate electricity are using wind turbines and using wind and water.
The one kind of electricity generation that does not include spinning a wheel of magnets, as Hellerman put it, is solar power.
From there, the two moved on to explain how AC and DC are ways to transport power and what the differences are.
In DC, electricity moves in a single, constant direction. AC power involves electricity alternating between a positive and negative flow.
Edison, who invented DC power, and Tesla, who invented AC power, feuded over whose invention would end up powering America.
Tesla and his AC power won out in the end, in large part due to AC power being more efficient for traveling long distances, Hellerman said.
To demonstrate this, she had four students volunteer into two teams, one DC and one AC. Each team had a ball representing an electron they had to pass back and forth.
Team DC had to run a loop around Hellerman before passing it to their partner while AC team members simply tossed the ball back and forth.
After the two teams competed, they compared how often they passed the ball back and forth and AC won with about 24 to DC’s score of about six.
However, DC power is still used today, Hellerman pointed out. While AC is good for transmitting power, DC is good for storing it.
“It turns out that DC power is the only kind of electricity that can be stored in a battery,” Hellerman said. “Even when you plug something into the wall, your charger is taking AC power from the wall and converting it to DC power.”
That is because in a battery, electrons flow in a single direction from the positive to the negative terminals to generate electricity, according to MIT’s School of Engineering’s website.
Tesla and Edison’s feud came to a head when they fought over who would light the 1893 Chicago World’s Fair.
“In the end Nikola Tesla was chosen because his electricity was easier to produce and it was a lot cheaper to produce,” Meyer said.
To wrap things up, the presenters brought out a 5-foot-tall Tesla coil, turned off the gym lights and showed the Jefferson students a shocking light show.
Connor Cummiskey can be emailed at firstname.lastname@example.org.