Their job is to convert high-voltage alternating current from the mains into low-voltage direct current for mobile phones, laptops, iPods and other electronic gadgets.

ECONOMIST: How a boring gadget saved $2 billion-worth of electricity

They can carry five to 20 times more current in the same unit area while reducing the amount of energy lost as heat by 75-97% (depending on whether the current is alternating or direct), even after accounting for all the nitrogen-cooling paraphernalia.

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Even Thomas Edison bet badly, as in his development of direct-current electricity that proved inferior to alternating current.

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