Edison, Tesla, and a really stupid woman in Iowa
Everyone remembers Thomas Edison as the man who invented the light bulb (at least, the first commercially successful one) but few know about his fight with Westinghouse over direct current. It all started when he hired a young scientist named Nikola Tesla. But what does that have to do with a stupid woman in Iowa? Read on…
Edison set Tesla on the task of fixing the electrical generator on a ship. He told Tesla; “Fix that really fast and I’ll give you a thousand dollars,” or something of the kind. And Tesla did, saving the shipping company from defaulting on a contract. But Edison reneged, saying “Can’t you take a joke, Nikola?”
Not smart, Tom. Nikola may have been an unhealthy neurotic with a thick foreign accent but he had the kind of mind Edison’s company needed. Tesla and his mind went over to Westinghouse, where George Westinghouse put him to work on research projects.
Tesla knew, for instance, that alternating current (AC) would travel much farther than direct current (DC), so he invented a rotating-field motor that could use AC. Edison preferred DC, no doubt because it galled him to pay licensing for the rotating-phase motor.
For a time the two companies were locked in a technological battle similar to VHS vs Beta, or Windows vs Macintosh; complete with ad campaigns, public stunts, and dirty tricks. As we all know, alternating current won – not that it ultimately held back Edison’s company much.
But how fast should alternating current… alternate? 60 cycles seemed logical, since there are sixty minutes in an hour and 60 seconds in a minute. It simplified the making of electric clocks, but by unhappy coincidence, 60 cycles is just about right to trigger heart fibrillation in a person who is electrocuted. Yet, it became the standard for the US electrical system.
Fast-forward to Little Sioux, Iowa, in 2005.
“A woman in this western Iowa town died Friday, apparently while trying to drive worms out of the ground with a homemade shocking device, officials said.
Harrison County Sheriff Terry Baxter said the woman, who was in her late 40’s, had a 2-foot metal shaft that was wired to an extension cord and secured with tape. Such rods are used to send electricity into moist soil, which forces night crawlers out of the ground.
“It’s not uncommon in our area,” Baxter said.
Baxter said the woman apparently was standing in water on saturated ground and was electrocuted.”
Tribune News Services
Y’know, hon, most people use a car battery for worm harvesting. It brings the worms up just fine, and as Tom Edison demonstrated in his anti-AC smear campaigns… it’s a heck of a lot safer.
“Tesla knew, for instance, that alternating current (AC) would travel much farther than direct current (DC), so he invented a rotating-field motor that could use AC.”
Certainly this is true from a technological point of view, but not from a physical point of view. If I remember my physics correctly, per watt (or maybe per joule), resistance is proportional to voltage and to the square of amperage. Thus to reduce resistance, voltage should be high, while amps should be low. It’s just a lot easier to build step-up transformers for AC than DC.
I’m amazed that people do this with rods and electricity. And why drive the worms out…. I thought they were good for the soil?
I’m still reading a book on Tesla’s life. He was done over again and again by people not paying him what he was owed and yet he kept going on. There’s a model of perserverance there!
And you know Tesla did a lot of showmanship to demonstrate that AC was actually safer than DC by passing the current through his body but he didn’t do the prattish thing of standing in water.
To quote Edison in “Jimmy Neutron, Boy Genius”: “Well knock 50 points off my IQ and call me Tesla!”
I’m a big Tesla admirer, but I did laugh at the quote. Too bad for Edison that he couldn’t see past his own greed.
Here’s one good reason: fishing!
Until now I’d never heard of shocking them, but as a kid I dug plenty of night crawlers out of the ground our backyard to use for bait. Man, those were the days…
This gal’s a shoe-in for a Darwin Award though. Heh.
Lucas I think you mean Power equals Resistance x Current squared. Resistance is an intrinsic property of matter, and will be relatively constant unless you try to jam too much current through something. However, real circuit are not quite linear. Resitance will vary with temperature and therefore with current.
The device that I remember consisted of two brass rods each with a wooden handle, and a lamp cord with the cloth outer cover cut back far enough so that you could separate the two rods. I remember my buddy’s father jamming them in the ground and then plugging into an AC outlet. (The ground was sufficiently dry.) The car battery is a far better idea.
We were taught that, given roughly the same voltage, DC is more dangerous. When you get an electrical shock your muscles seize. With AC you have 120 opportunities per second to let go. The Diesel Electric Submariners had a an expression—“across the breakers”—meaning having an serious problem with something. (The main engines were powered by roughly 120 VDC.)
I grew up among other displaced Hillbillies in Pontiac, Michigan and it was common practice to use a car battery to drive nightcrawlers to the surface for fish bait. I can remember a lot of my neighbors doing that on a regular basis.
Anyway, I’ve always been fascinated with the battle between Edison and Tesla over which form of electric service would go on to be successful. Tesla was easily a better scientist that Edison, but Edison was a better businessman it seems.
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does anyone know why electric cars use ac rather than dc motors?
:question:
I’m not sure exactly – my guess would be it’s easier to regulate AC than DC at those amperages. Here is Toyota’s white-paper on the Hybrid Synergy drive that gives some details. Maybe someone can give a more engineering-related reason.
An AC motor of an equivalent size rating is A LOT lighter, smaller, and significantly less expensive than the DC version of the same motor. This is mostly because the AC version (as Tesla first discovered) has no need for brushes or commutators.
Cars use DC motors because they are simpler, don’t have to add extra equipment to convert the stored electricity (DC) to AC for use. and given power density of sources (batteries) is at a premium, you don’t want to waste a watt if you can help it (in the conversion process from AC to DC.
Also, the cars use regenerative braking to kick a bit of a charge back into the batteries on deceleration.
aaron
That’s what I thought too. Then I read the Toytoa white paper. Page 10:
Power Control Unit The power control unit contains an inverter that converts the DC from the battery into an AC for driving the motor and a DC/DC converter for conversion to 12V. In THS II, a high-voltage power circuit that can increase the voltage from the power supply to 500V, has been added. Based on the relationship
of Power = Voltage x Current, increasing the voltage makes it possible to reduce the current, which in turn makes it possible to reduce the size of the inverter. Also, because the control circuits have been integrated, the size of the
power control unit itself has remained almost the same as before.
So the Prius uses an AC motor. Then it has another stepdown transformer to produce the small amount of 12v that is needed for automotive-type accessories like the radio. Interesting.
need to make electric ground rod to chase away moles instead of worms will it work if you know right way with out shock to death please send how to make with car battery
SEND INSTRUCTIONS TO MAKE ELECTRIC GROUND ROD TO CHASE AWAY MOLES.
I would think moles would be more sensitive to sound than anything. You could try one of those mole-chasers.
Or you could just set some speakers on the ground and play top 40 pop music…