I don't know why the parent was downvoted, it's an honest question that's encouraged lots of high-quality responses. Here's mine: Faraday's law of induction:

I don't know why the parent was downvoted, it's an honest question that's encouraged lots of high-quality responses. Here's mine: Faraday's law of induction: A changing electric field through a coil induces a current in that coil. Induction is how transformers work. Hopefully you believe that attaching things to a transformer's output can put a load on its input. Since this device and transformers both use induction, if it can happen in a transformer, it can happen with this technology.