In order to create transformers it was necessary to study the properties of materials: non-metallic, metallic and magnetic.
Alexander Stoletov took the first steps in this direction. He discovered the hysteresis loop and the domain structure of ferromagnet (1880s).
Hopkinson brothers developed the theory of electromagnetic circuits.
In 1831, the English physicist Michael Faraday discovered the phenomenon of electromagnetic induction, which underlies the operation of an electrical transformer, during his fundamental research in the field of electricity.
A schematic representation of the future transformer first appeared in 1831 in the works of Faraday and Henry. However none of them noted in their device any change in voltages and currents, in other words alternating current transformation.
In 1848 Heinrich Daniel Ruhmkorff invented an induction coil of a special design. It was the transformer prototype.
On November 30, in 1876, Pavel Yablochkov received the world’s first patent for his electric candle – considered a first-ever application of the transformer. Yablochkov invented a lighting system based on a set of induction coils where the primary windings were connected to a source of alternating current. The secondary windings could be connected to several ‘electric candles’ (arc lamps) of his own design.