Crystal radio

Okay kiddo, imagine you want to listen to your favorite song on the radio. But instead of using batteries, electricity, or anything else fancy, all you need is a wire, a crystal, and some headphones.

First, you need to make a coil by wrapping wire around a cardboard tube, like a toilet paper roll. Then, you attach one end of the wire to a metal rod, which will act like an antenna and pick up radio signals from the air.

Next, you attach the other end of the wire to a thin piece of metal called a diode, which is connected to a crystal. The crystal can only let the signals flow in one direction, which means it filters out unwanted noise and amplifies the useful signal.

Finally, you attach your headphones to the crystal and tune the metal rod until you hear your favorite song. That's it! You just made your very own crystal radio and started picking up signals from the airwaves.