Electrical transformers .An electrical transformer consists of two (or more) wire coils wrapped around the same core made of a very high magnetic permeability material, such as iron or silicon electrical steel. When alternating current (AC) is passed through the first coil it creates magnetic flux in the core which in turn induces current in the second coil, as it follows from the Faraday's law. Depending on the ratio of the turns in the two coils, voltage induced in the second core can be greater or less than voltage applied to the first coil. The most common household use of electrical transformers is in AC power adapters that transform mains high voltage (110-220V) AC power to several Volts DC power suitable for powering small electric and electronic appliances. Shown here are transformers of a design commonly referred to as the E-I transformer. Photo Nov 2008.