There's no switch on it. No crank, no shake, no solar cell soaking up sun. You just wrap your fingers around it, and it lights up. That's the whole instruction manual. The device belongs to Ann Makosinski, who was fifteen and in Grade 10 at St. Michaels University School in Victoria, British Columbia, when she built it. She called it the Hollow Flashlight, and in 2013 it won her age category at the Google Science Fair. The materials cost about $26. The physics behind it, though, is worth far more than that.
