Speaker 1: Welcome to Brainstuff from house stuff works dot com where
Speaker 1: smart happens. Hi'm Marshall Brain with today's question, how can
Speaker 1: an electric toothbrush recharge its batteries when there are no
Speaker 1: metal contacts between the toothbrush and the recharging base. If
Speaker 1: you own an electric toothbrush, there's a good chance that
Speaker 1: it has a completely sealed toothbrush unit. The toothbrush rests
Speaker 1: on the charger without any metal contacts to connect the
Speaker 1: toothbrush to the base. This has the great advantage of
Speaker 1: allowing the toothbrush to be completely sealed so that water
Speaker 1: can't enter through those exposed contacts. It also avoids any
Speaker 1: problems with water getting into the contacts and shorting out
Speaker 1: the charger. This sort of sealed arrangement is called inductive charging. Essentially,
Speaker 1: the toothbrush and the base form a two part transformer,
Speaker 1: with the base having one part of the transformer and
Speaker 1: the toothbrush having the other. When you slide the toothbrush
Speaker 1: onto that base, the complete transformer is created and charge
Speaker 1: can flow to the batteries. The base contains one of
Speaker 1: the coils of the transformer and the metal bar the
Speaker 1: toothbrush contains the second coil. When you drop the toothbrush
Speaker 1: onto the base, you create the complete transformer. Do you
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