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) as such: "I'd go in and say, 'The song has gone, whatever it is you liked about this song is not there anymore. Sometimes, for example, the song would have disappeared under layers of overdubs." "Ultraviolet (Light My Way)" is written in a 4/4 time signature. The lyrics of "Ultraviolet (Light My Way)" are addressed to a lover, and imply that their relationship is threatened by some sort of personal or spiritual crisis, coupled with a sense of unease over obligations. Indeed, lead vocalist Bono has called the song "a little disturbed". The song opens with 45 seconds of soft