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 communication in butterflies some species this distinction is not seen at all times, and UV patterns may vary visually depending on the position of reflecting light. This can be seen in the common brimstone, where males will exhibit male or female patterns of iridescence with different positions, distances, and angles of light - this is known as the "gynandromorphic" effect. The ultraviolet communication system employed by butterflies is also used an indicator of male sex to other rival males in the butterfly, "Colias eurytheme". In this species, only males are able to reflect ultraviolet light off the dorsal side of their wings, while