Electrical energy flows into the toaster from a wire plugged into the domestic electricity supply. The electric current flows through a series of thin filaments connected together but spaced widely enough apart to toast the whole bread surface. The filaments are so thin that they glow red hot when the electricity flows through them. Like a series of small radiators, the filaments beam heat toward the bread in the toaster. The steady supply of heat rapidly cooks the bread. There are filaments on each wall of the toaster so the two sides of the bread cook at the same time.
