CHAMPVA is a Department of Veterans Affairs program; TRICARE is a regionally managed health care program for active duty and retired members of the uniformed services, their families, and survivors. In some cases a Veteran may appear to be eligible for both/either program on paper.
Quick Answer. Michael Faraday discovered the law of electromagnetic induction in 1831. He realized that current in a circuit can be induced by changing the magnetic field. Faraday tested it by wrapping a paper cylinder with a wire and connecting the coil to a galvanometer. Faraday then moved the magnet back and forth inside the cylinder.
Throughout the rest of the 19th century, scientists would develop actual transformers that were used to harness the magnetic power that Faraday observed. Already by the 1870s, academics working on electricity were building coils that in many respects resemble the transformers still in use today.