photoelectric element in a sentence

1. By the early 1930s the movie industry had almost universally adopted the " sound-on-film " technology ( developed by Western Electric and others ) in which the audio signals picked up by the microphones were modulated via a photoelectric element to generate a narrow band of light, of variable width or height, which was then captured on a dedicated'audio'strip on the edge of the film negative, as the images were being filmed.
2. It's difficult to find photoelectric element in a sentence.