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kids infobits

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Welcome to Britannica School , a safe, up-to-date, and age-appropriate information resource for Elementary, Middle, and High School.

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Learn more and understand better with BrainPOP's animated movies, games, playful assessments, and activities covering Science, Math, History, English, and more!

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ted talks

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Marco Tempest: The electric rise and fall of Nikola Tesla

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Combining projection mapping and a pop-up book, Marco Tempest tells the visually arresting story of Nikola Tesla -- called "the greatest geek who ever lived" -- from his triumphant invention of alternating current to his penniless last days.

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pb

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PBS: Tesla - Master of Lightning: Coming to America

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ted ed

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The science of static electricity - Anuradha Bhagwat

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We've all had the experience: you're walking across a soft carpet, you reach for the doorknob and ... ZAP. But what causes this trademark jolt of static electricity? Anuradha Bhagwat sheds light on the phenomenon by examining the nature of matter.

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This story is part of a special series that explores energy issues. For more, visit The Great Energy Challenge.
The steady roll of the Mississippi River, inspiration for so many great American songs and stories, also could light homes and power businesses, say developers who aim to turn that idea into reality.

The proposed project to convert the torrent beneath North America's largest river into electricity is one of dozens of efforts across the United States to harness the energy produced by the constant surge of tides and rivers. These new proposals differ from traditional hydroelectric projects, which rely on dams to control the water's flow.

Free Flow Power (FFP) of Gloucester, Massachusetts, has especially high hopes for its Mississippi project in part because of the river's fresh-if not exactly clean-water. Efforts to harness energy offshore in salt water face greater difficulty, because of the changing direction of the tides and the higher risk of equipment corrosion and fouling.
Turbines Invisible from Shore
The current of the Mississippi River flows past New Orleans at around 4 mph (6 kmh) at times, according to data from the U.S. Army Corps of Engineers. Since moving water can produce 800 times more energy than wind, the river could turn the blades of submerged turbines to produce electricity for thousands of homes-at least, that's the theory.

But developers are still trying to determine whether the technology is commercially feasible.

FFP spokesman Jon Guidroz said his company was pleased with the results of a recently concluded six-month test of a turbine tethered to a dock near Baton Rouge. The tests were part of the company's plan to start producing electricity in 2013. But Guidroz would not discuss details of the test, citing concerns about confidentiality. He also indicated it was too early to discuss how much power the company could produce.

Eventually, however, FFP hopes to attach turbines to concrete pilings anchored deep in the Mississippi. The turbines would be invisible from the shore, and the only evidence of their presence would be cables emerging from the water.

Each turbine would have seven blades with a diameter of about 10 feet (3 meters). The blades would turn very slowly to minimize the danger to fish.

Designers sacrificed some efficiency to make the turbines more environmentally friendly, Guidroz said. "We increased the distance between the blades and removed all the lubricants," he said. "The turbines are lubricated by water. If a bearing breaks, it's not leaking anything into the river.

"The turbines are much smaller than a windmill, and spin much slower."

The projects to generate hydrokinetic electricity must be approved by the Federal Energy Regulatory Commission (FERC) in Washington, D.C. FERC spokeswoman Celeste Miller said the agency first saw "a trickle" of applications for federal permission to develop the technology in 2004.

That trickle has increased since then, and FERC has 134 applications on file. The applications include projects on the Mississippi and Ohio rivers, as well as offshore projects along the U.S. Atlantic and Pacific coasts and Alaska and Hawaii.

Henry Dormitzer, FFP's chief financial officer, said the development of hydrokinetic electricity would be helped by changes in federal tax laws. Current law allows extended tax credits to developers of wind and solar power. Hydrokinetic developers need similar laws, he said.

"The licensing period is so long that developers need a stable, predictable tax structure," Dormitzer said.

Questions also have been raised about possible environmental impacts. A 2008 report submitted to Congress by the U.S. Department of Energy noted that hydrokinetic technology "has the potential to impact fish and marine mammals." Besides the danger of large turning blades, noise from the turbines could "disrupt" the behavior of marine animals far away, the report said.

Rupak Thapaliya, coordinator for the Hydropower Reform Coalition, a conservation group in Washington, D.C., said more research is needed. "I imagine that if you put something like that into the water, it could have an impact and change the behavior" of marine animals, he said.

Peter Asmus, a senior analyst with the market research firm Pike Research, said experiments on hydrokinetic technology are only being done in North America. He said that's probably because the Mississippi River is one of the few places the technology could be cost-effective, due to the large size of the resource and plenty of nearby industrial development that needs power.

Asmus said the technology's potential could be "huge," but it's too early to tell if it is economically feasible.

"The next five years is the key to determining whether this is big or whether it's only a flash in the pan," he said.

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This story is part of a special series that explores energy issues. For more, visit The Great Energy Challenge . The steady roll of the Mississippi River, inspiration for so many great American songs and stories, also could light homes and power businesses, say developers who aim to turn that idea into reality.

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Credit: Karl Tate/Live Science

Nikola Tesla would have celebrated his 158th birthday today (July 10).

The Serbian-American scientist was a brilliant and eccentric genius whose inventions enabled modern-day power and mass communication systems.

His nemesis and former boss, Thomas Edison, was the iconic American inventor of the light bulb, the phonograph and the moving picture. The two feuding geniuses waged a "War of Currents" in the 1880s over whose electrical system would power the world - Tesla's alternating-current (AC) system or Edison's rival direct-current (DC) electric power.

Amongst science nerds, few debates get more heated than the ones that compare Nikola Tesla and Thomas Edison. So, who was the better inventor?

"They're different inventors, but you can't really say one is greater, because American society needs some Edisons and it needs some Teslas" said W. Bernard Carlson, the author of "Tesla: Inventor of the Electrical Age" (Princeton Press, 2013).

From their starkly different personalities to their lasting legacies, here's how the two dueling inventors stack up. [ Vote: Tesla vs. Edison - Who Was the Greatest Inventor of All Time?]

Most brilliant

Tesla had an eidetic memory, which meant he could very precisely recall images and objects. This enabled him to accurately visualize intricate 3D objects, and as a result, he could build working prototypes using few preliminary drawings.

"He really worked out his inventions in his imagination," Carlson told Live Science.

In contrast, Edison was more of a sketcher and a tinkerer.

"If you were going to [the] laboratory and watch him at work, you'd find he'd have stuff all over the bench: wires and coils and various parts of inventions," Carlson said.

In the end, however, Edison held 1,093 patents, according to the Thomas Edison National Historic Park. Tesla garnered less than 300 worldwide, according to a study published in 2006 at the Sixth International Symposium of Nikola Tesla. (Of course, Edison had scores more assistants helping him devise inventions, and also bought some of his patents.)

Most forward thinking

Though the light bulb, the phonograph and moving pictures are touted as Edison's most important inventions, other people were already working on similar technologies, said Leonard DeGraaf, an archivist at Thomas Edison National Historical Park in New Jersey, and the author of "Edison and the Rise of Innovation" (Signature Press, 2013).

"If Edison hadn't invented those things, other people would have," DeGraaf told Live Science.

In a shortsighted move, Edison dismissed Tesla's "impractical" idea of an alternating-current (AC) system of electric power transmission, instead promoting his simpler, but less efficient, direct-current (DC) system.

By contrast, Tesla's ideas were often more disruptive technologies that didn't have a built-in market demand. And his alternating-current motor and hydroelectric plant at Niagara Falls - a first-of-its-kind power plant - truly electrified the world.

Tesla also spent years working on a system designed to wirelessly transmit voices, images and moving pictures - making him a futurist, and the true father of radio, telephone, cell phones and television. [ Creative Genius: The World's Greatest Minds]

"Our entire mass communication system is based on Tesla's system," said Marc Seifer, author of "Wizard: The Life and Times of Nikola Tesla," (Citadel Press, 2001).

Unfortunately, Tesla's grand scheme failed when his financial backer, J.P. Morgan, became fed up with years of failure.

Biggest impact

Edison's enduring legacy isn't a specific patent or technology, but his invention factories, which divided the innovation process into small tasks that were carried out by legions of workers, DeGraaf said. For instance, Edison got the idea for a moving picture camera, or kinetoscope from a talk by photographer Edward Muybridge, but then left most of the experimentation and prototyping to his assistant William Dickson and others. By having multiple patents and inventions developing in parallel, Edison, in turn, ensured that his assistants had a stable financial situation to continue running experiments and fleshing out more designs.

"He invents modern innovation as we know it," DeGraaf said.

Tesla's inventions are the backbone of modern power and communication systems, but he faded into obscurity later in the 20th century, when most of his inventions were lost to history. And despite his many patents and innovations, Tesla was destitute when he died in 1943.

Best dinner party guest

At the height of his career, Tesla was charismatic, urbane and witty. He spoke several languages and counted writers Mark Twain and Rudyard Kipling, and naturalist John Muir as friends, according to Seifer.

"He moved in very high circles," Seifer said.

But Tesla could also be haughty and was known to be a hygiene freak. In his later years, his obsessive tics (such as his fear of women's earrings) grew stronger, and he died penniless and alone in a hotel in New York City, Seifer said.

Edison, meanwhile, was hard of hearing and introverted, with few close friends.

Edison also had a mean streak, which he amply displayed in his vicious attacks against Tesla during the War of Currents. He also gave advice on how to build the first electric chair using direct current (DC), going into gory detail about the techniques needed to do the deed, Seifer said.

Most fashionable

Tesla was tall, slender and imposing, with a dashing moustache and an impeccable sense of style, Carlson said. His top hat and tails are even on display in a museum in Serbia.

By contrast, Edison was known to be a bit of a slob.

"We're not really interested in seeing what Edison wore, because it was pretty forgettable," Carlson said.

Edison even wore shoes two sizes too large so that he could slip into and out of them without stooping down to untie them, Carlson said.

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Nikola Tesla vs. Thomas Edison: Who Was the Better Inventor?

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Nikola Tesla would have celebrated his 158th birthday today (July 10). The Serbian-American scientist was a brilliant and eccentric genius whose inventions enabled modern-day power and mass communication systems. His nemesis and former boss, Thomas Edison, was the iconic American inventor of the light bulb, the phonograph and the moving picture.