Chemestry: Electroplating

Electroplating is using electrical current to coat a metal with a thin layer of another metal.

The anode and cathode in the electroplating cell are both connected to an external supply of direct current - a battery or, more commonly, a rectifier. The anode is connected to the positive terminal of the supply, and the cathode (article to be plated) is connected to the negative terminal. When the external power supply is switched on, the metal at the anode is oxidized from the zero valence state to form cations with a positive charge.

These cations associate with the anions (with a negative charge) in the solution. The cations are reduced at the cathode to deposit in the metallic, zero valence state. The build up of these atoms create a thin layer.

Sources: Wikipedia