Machine Design

Wireless Recharge

With cordless phones, wireless internet, and cell phones, the idea of wireless power is not a novel one.

Julie Kalista
Online Editor

Researchers present a graphic illustrating how magnetism can transmit energy wirelessly. They used theoretical calculations and computer simulations to find ways to recharge electronics wirelessly.
Photo Credit: Donna Coveney
In fact, scientists have known for almost two centuries that wires do not have to be in physical contact to carry electric power. Electric motors and transformers use coils to transmit energy to each other through electromagnetic induction. Later, scientists disccovered electromagnetic radiation in the form of radio waves. Transferring energy this way is inefficient because waves spread in all directions, so energy is lost.

Marin Soljacic, assistant professor in Massachusettes Institute of Technology, came up with an idea that could have cell phones and laptops recharging themselves wirelessly. The theory says non-radiative energy can send power to devices without wiring. Soljacic and his team believe that non-radiative wireless devices would have a limited range, but that a laptop could be charged within a few meters of the power source, so placing one source in each room would provide coverage throughout one's home.

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