Complex sentence: Coolidge went to work as a researcher at General Electric new research laboratory in 1905, where he conducted critical experiments that led to the use of tungsten as filaments in light bulbs.
Split into simpler sentences: Coolidge went to work as a researcher for General Electric new research laboratory in 1905. In the early days of his employment as a researcher for the General Electric Company, he conducted critical experiments that led to the use of tungsten as filaments in light bulbs.