Explain how the charger of an electric toothbrush works, despite insulation of a plastic layer on both the charger and the toothbrush for water resistance:

Question 1

charger of an electric toothbrush step 1

Answer 1

The charging of an electric toothbrush uses the principle of transformers.

Question 2

charger of an electric toothbrush step 2

Answer 2

There is a wire coil in the charger that takes the electricity from the mains supply, and a second coil inside the toothbrush.

Question 3

charger of an electric toothbrush step 3

Answer 3

When the alternating potential difference from the mains supply is applied across the primary coil in the charger, an alternating current is generated in the secondary coil.

Question 4

charger of an electric toothbrush step 4

Answer 4

This alternating current creates a continuously changing magnetic field in the iron core, that also passes through the secondary coil.

Question 5

charger of an electric toothbrush step 5

Answer 5

The changing magnetic field passing through the secondary coil in the toothbrush induces an alternating potential difference in the secondary coil.

Question 6

charger of an electric toothbrush step 6

Answer 6

This alternating potential difference produces an alternating current in the secondary coil that charges the battery of the toothbrush.