Wires do a lot of credit when it comes to transmitting electricity, but they also have downsides. After all, who doesn’t hate plugging and unplugging cords for phones or other rechargeable devices? This is a hassle. Wires also present a challenge for power companies: These companies must work to push the voltages applied to transmission cables to very high values to avoid consuming much of the power during transmission. When powering public transport such as electric trains and trams, the wires need to work with rolling or sliding contacts that are cumbersome to maintain, can create sparks, and in some cases can cause problematic pollutants. Many people are eager to solve these problems – wireless charging has seen widespread adoption over the past decade, mainly in portable consumer electronics, but also in vehicles. While a wireless charger saves you from having to repeatedly connect or unplug the cable, the distance that power is transferred this way is very short. In fact, when the air gap reaches a few centimeters, it can be difficult to charge or power a device, let alone a few meters away. Is there really no practical way to transmit power over greater distances without wires? For some, the whole concept of wireless power transfer is reminiscent of that photo of Nikola Tesla, with high-voltage coils emitting tiny lightning bolts behind him. This is not a silly association. Tesla did ponder the idea of using the ground or the atmosphere in some way as a conduit for power transmission over long distances, but the plan didn’t work out. His dream was to transmit electricity over long distances without wires.
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