Film stock produce only a very slight chemical change, proportional to the amount of light absorbed by each crystal. This creates an invisible latent image in the emulsion, which can be chemically developed into a visible photograph. In addition to visible light, all films are sensitive to X-rays and high-energy particles. Most are at least slightly sensitive to invisible ultraviolet (UV) light. Some special-purpose films are sensitive into the infrared (IR) region of the spectrum. In black-and-white photographic film there is usually one layer of silver salts. When the exposed grains are developed, the silver salts are converted to metallic silver, which
Ultraviolet (Light My Way) it. "Ultraviolet" played a featured role during the encores of the group's 1992–1993 Zoo TV Tour, 2009–2011 U2 360° Tour, and the Joshua Tree Tour 2017. "Ultraviolet (Light My Way)" began as two different demos, one variously called "Ultraviolet" and "69" (which eventually evolved into the B-side "Lady with the Spinning Head") and an alternately arranged demo called "Light My Way". Over the course of the recording sessions, U2 added various overdubs to the song, but producer Brian Eno believed these additions negatively impacted the track. Eno aided the group in editing down the song, and he explained his assistance