Photoacoustic effect a rotating slotted wheel. He noticed that the resulting acoustic signal was dependent on the type of the material and correctly reasoned that the effect was caused by the absorbed light energy, which subsequently heats the sample. Later Bell showed that materials exposed to the non-visible (ultra-violet and infra-red) portions of the solar spectrum can also produce sounds and invented a device, which he called "spectrophone", to apply this effect for spectral identification of materials. Bell himself and later John Tyndall and Wilhelm Röntgen extended these experiments, demonstrating the same effect in liquids and gases. However, the results were too
Ultraviolet (Light My Way) Ultraviolet (Light My Way) "Ultraviolet (Light My Way)" is a song by Irish rock band U2 and the tenth track from their 1991 album "Achtung Baby". Ostensibly about love and dependency, the song also lends itself to religious interpretations, with listeners finding allusions to the Book of Job and writers finding spiritual meaning in its invocation of the light spectrum. The song's composition and recording incorporate both serious and throwaway elements, in keeping with the rest of "Achtung Baby". While not released as a single, the song has appeared in two films and a U2 business venture was named after