Do electric toothbrush chargers use energy when the toothbrush isn't in place? © Getty Images

Do electric toothbrush chargers use energy when the toothbrush isn’t in place?

As you dutifully brush your teeth morning and night, your toothbrush stand leaks heat.

Asked by: Thomas Hampton, by email

Advertisement

An induction charger is two halves of a transformer, with a coil in each section. The mains electricity in the coil of the base induces a trickle of current in a smaller coil in the toothbrush, to charge the battery.

A perfect transformer would take no power with the two sections separated. But, in reality, coils are ‘lossy’, meaning that some power is used up as heat, even when none is being drawn via the other coil.


Advertisement

Subscribe to BBC Focus magazine for fascinating new Q&As every month and follow @sciencefocusQA on Twitter for your daily dose of fun science facts.