Dear Amy: How do electric toothbrushes charge through plastic? I thought plastic couldn't conduct electricity. — Drew, Austin, Texas
Dear Drew: Most chargers and electronic devices connect through metal contact points, such as a charger that plugs into a port on a cell phone. These metal contact points aren't safe for chargers in the bathroom, because they could easily get wet and shock someone. Luckily, toothbrush chargers can use induction instead.
Both the toothbrush and charger have coils of wire inside them. When an electric current flows through the charger's coil, it creates a magnetic field around the wire. The electricity we get from an outlet has an alternating current, meaning it changes direction many times per second. This causes the magnetic field around the coiled wire in the charger to change direction, too.
When your toothbrush is placed on the charger, the coiled wire inside the toothbrush is affected by the magnetic field in the charger and causes an electric current to flow through the wire. This electric current is used to charge the toothbrush battery. For more information about how induction works, visit www.physics4kids.com/files/elec_faraday.html.
Ask Amy a Question