Dear Science,

Does wireless electricity really work? Will it give us cancer? Will it turn me into a Spider-Man villain? Tell me! I need to know!

Dear Reader,

Wireless electricity has been around since 1836. Nicholas Callan's experiment started it all; when he connected or disconnected a battery to one loop of wire around an iron bar, he noticed a spark between the free ends of a second coil of wire wrapped around the same bar. Magic! The electricity wirelessly transmitted between the coils. It has everything to do with the funny relationship between electricity and magnetism. Electrical currents make magnetic fields (thanks William Sturgeon) and changing magnetic fields can induce currents in wires (thanks Michael Faraday). When Nick connected or disconnected the battery from the first coil of wire, the magnetic field (carried down the iron rod) changed. When the magnetic field changed around the second coil of wire, an electric current was created, causing the spark. Every power plant still works by changing a magnetic field around coils of wire. Wireless electricity in your home is the same process on a smaller scale. Induction cooktops and wireless chargers for electric toothbrushes and cell phones all work by changing a magnetic field in one place to create a current in another.

So, if the technology is so old, why do we still have a rat's nest of wires to power everything? Because magnetic fields rapidly lose strength with distance. As radio waves, a tiny bit of power can be transmitted huge distances, but getting enough power to run a lightbulb over a long distance is impractical; wires are just more efficient. Even newer technologies—focused microwaves, or lasers—still have not made wireless electricity practical. We went on to create radio, television, and wireless Ethernet instead—where tiny amounts of induced current are used to communicate rather than power. As a result, we live in a world bathed in current-inducing electromagnetic fields.

So, are we all going to die from radio-induced cancer? For every study showing a weak connection between exposure to electromagnetic fields and cancer, another exists showing a lack of connection; any risk must be pretty tiny. Science finds it amusing when people blissfully engage in a wide variety of life-shortening activities—smoking, eating trans-fat fried foods—only to stay awake at night fretting over electromagnetic fields. You are much more likely to die from someone gabbing on a cell phone while driving a car than from testicular cancer from your pocketed cell phone.

So, sorry, no superpowers will come forth from wireless electricity. The War of Currents, fought between Edison, Tesla, and Westinghouse—involving artificial lightning, Niagara Falls, and ghastly intentional electrocutions of livestock and prisoners—remains the only superhero battle in electricity. recommended

Galvanizingly Yours,


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