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An electric toothbrush can charge its battery even without metal contacts involved.
Getty ImagesIf you own an electric toothbrush, it is likely designed with a fully sealed unit. The toothbrush rests on the charger without any metal contacts connecting it to the base. This feature ensures that water cannot enter through exposed contacts, thus preventing any potential short-circuiting of the charger.
This system is referred to as inductive charging. The toothbrush and charger together form a two-part transformer, where the base holds one part and the toothbrush holds the other. When the toothbrush is placed on the charger, the transformer circuit completes and allows charging to occur.
The base holds one of the coils and the metal bar, while the toothbrush contains the second coil. By placing the toothbrush onto the base, you complete the transformer circuit!
