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Transformers  Medium-sized electricity transformer supplying a
small village.  Electricity transformers  by Chris Woodford.
Last updated: January 15, 2014.  The mighty power lines that
criss-cross our countryside or wiggle unseen beneath city
streets carry electricity at enormously high voltages from power
plants to our homes. It's not unusual for a power line to be
rated at 400,000 to 750,000 volts! But the appliances in our
homes use voltages thousands of times smaller—typically just 110
to 250 volts. If you tried to power a toaster or a TV set from
an electricity pylon, it would instantly explode! (Don't even
think about trying, because the electricity in overhead lines
will almost certainly kill you.) So there has to some way of
reducing the high voltage electricity from power plants to the
lower voltage electricity used by factories, offices, and homes.
The piece of equipment that does this, humming with
electromagnetic energy as it goes, is called