I made the transition from regular to electric toothbrush a month or two ago, and aside from the noticeable improvement in my oral hygiene, I've been thinking about how the toothbrush charges. I understand the manufacturers motivation for not using exposed electrical contacts, as such a design may let water inside, however i found the alternative to be far more puzzling. when you want to charge it, conveniently, you only have to place it on the peg protruding from the base plugged into the wall. With a design including no electrical contact between base and brush, i was confused as to how energy was passed between the devices, however now i think i have an answer. what i think is that the energy in the base is sent to the brush through a magnetic field. there are two coils, one in the brush, and one in the base. when the base is energized, the magnetic field it creates envelops the brush coil, inducing a current, and charging the battery. physics is truly everywhere.