1800---1875


 * William Herschel**




 * Born:** 15 November 1738
 * Died:** 25 August 1822

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He was a British composer, technical expert, and an astronomer Herschel became most famous for the discovery of the planet Uranus, as well as several of its major moons such as Oberon and Titania. He also discovered INFRARED RADIATION!!!! "On 11 February 1800, Herschel was testing filters for the sun so he could observe sun spots. When using a red filter he found there was a lot of heat produced. Herschel discovered infrared radiation by passing sunlight through a prism and holding a thermometer just beyond the red end of the visible spectrum. This thermometer was meant to be a control to measure the ambient air temperature in the room. He was shocked when it showed a higher temperature than the visible spectrum. Further experimentation led to Herschel's conclusion that there must be an invisible form of light beyond the visible spectrum."




 * THOMAS YOUNG**




 * Born:** 13 June 1773
 * Died**: 10 May 1829

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MOST IMPORTANT ACCOMPLISHMENT WAS THE WAVE THEORY OF LIGHT!! With the ripple tank he demonstrated the idea of interference in the context of water waves. With the two-slit, or double split experiments, he demonstrated interference in the context of light as a wave. In a paper entitled //Experiments and Calculations Relative to Physical Optics//, published in 1803, Young describes an experiment in which he placed a narrow card in a beam of light from a single opening in a window and observed the fringes of color in the shadow and to the sides of the card. He observed that placing another card before or after the narrow strip so as to prevent light from the beam from striking one of its edges caused the fringes to disappear. This supported the contention that light is composed of WAVES Young performed and analyzed a number of experiments, including interference of light from reflection off nearby pairs of micrometer grooves, from reflection off thin films of soap and oil, and from "Newton's Rings."

CHECK OUT THIS INTERACTIVE DOUBLE SPLIT WAVE EXPERIMENT'/EXPLANATION!!!!!! []


 * Joseph von Fraunhofer

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 * Born:** 6 March 1787
 * Died:** 7 June 1826

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One of the most talented lenscrafters of his time. Spend hours upon hours perfecting lenses and telescopes. He invented the device known as the spectroscope for observing the dark lines found in the visible spectrum, effectively founding the science of spectroscopy. "It was while he was perfecting his lenses that Fraunhofer made what was to behis most important discovery. In order to calibrate his instruments he wouldfocus them upon a bright candle. One day, however, he chose to use the lightfrom the sun. He was quite surprised to find a number of dark lines crossingthe sun's rainbow spectrum--lines that were not present in the spectra of candlelight. Fraunhofer's precise equipment enabled him to discern 574 individual lines in the spectrum of the sun." This was a massive breakthrough in the field of astronomy and led to the telescopes we have to this very day!!!