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.

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The resin within the carbon layers is laced with lithium ions, so that each layer acts like an electrode, causing the positively charged lithium ions to collect in one layer when a voltage is applied, and a current to flow when the sandwich is placed in a circuit.

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That is the reason why the current emphasis in China is on the construction of 500kv extra-high-voltage lines and long-distance power transmission.

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Power electronics modify the voltage, current or frequency of electricity in applications as diverse as solid-state lighting, intelligent motors and electric vehicles.

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Lethal electric fences, however, use a continuous current that can make a person lock on to the wire as voltage causes involuntary muscle contractions, paralysis and death.

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ABB's best trick is its ability to take electric current of any voltage and frequency, chop it up into tiny bits and reassemble it into the form needed.

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