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In 1877, Thomas Edison invented the phonograph. Unlike the phonautograph, it was capable of both recording and reproducing sound. Despite the similarity of name, there is no documentary evidence that Edison's phonograph was based on Scott's phonautograph. Edison first tried recording sound on a wax-impregnated paper tape, with the idea of creating a "telephone repeater" analogous to the telegraph repeater he had been working on. Although the visible results made him confident that sound could be physically recorded and reproduced, his notes do not indicate that he actually reproduced sound before his first experiment in which he used tinfoil as a recording medium several months later. The tinfoil was wrapped around a grooved metal cylinder and a sound-vibrated stylus indented the tinfoil while the cylinder was rotated. The recording could be played back immediately. The Scientific American article that introduced the tinfoil phonograph to the public mentioned Marey, Rosapelly and Barlow as well as Scott as creators of devices for recording but, importantly, not reproducing sound. Edison also invented variations of the phonograph that used tape and disc formats. Numerous applications for the phonograph were envisioned, but although it enjoyed a brief vogue as a startling novelty at public demonstrations, the tinfoil phonograph proved too crude to be put to any practical use. A decade later, Edison developed a greatly improved phonograph that used a hollow wax cylinder instead of a foil sheet. This proved to be both a better-sounding and far more useful and durable device. The wax phonograph cylinder created the recorded sound market at the end of the 1880s and dominated it through the early years of the 20th century.
How did the phonograph differ from the phonautograph?
A: capable of both recording and reproducing sound

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The Warnerke Standard Sensitometer consisted of a frame holding an opaque screen with an array of typically 25 numbered, gradually pigmented squares brought into contact with the photographic plate during a timed test exposure under a phosphorescent tablet excited before by the light of a burning Magnesium ribbon. The speed of the emulsion was then expressed in 'degrees' Warnerke (sometimes seen as Warn. or °W.) corresponding with the last number visible on the exposed plate after development and fixation. Each number represented an increase of 1/3 in speed, typical plate speeds were between 10° and 25° Warnerke at the time.
How much speed is associated with each degree Warnerke?
A: an increase of 1/3 in speed

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The company aims to reduce its external environmental impact through energy-efficient evolution of products, and also reduce its direct operational impact through energy-efficiency programs. Internal energy-efficiency programs reportedly save the company more than $3 million annually in energy-cost savings. The largest component of the company's internal energy-efficiency savings comes through PC power management: the company expects to save $1.8 million in energy costs through using specialized energy-management software on a network of 50,000 PCs.
What does Dell aim to reduce by creating energy efficient products?
A: external environmental impact

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By the verse Quran, 2:124, Shias believe that Imamah is a divine position always Imamah is accompanied by the word guidance, of course a guidance by God's Command.A kind of guidance which brings humanity to the goal. Regarding 17:71, no age can be without an Imam. So, according to the upper verse 1.Imamah is a position which is appointed by God and must be specified by Him 2.Imam is protected by a divine protection and no one exceles him in nobility 3. No age can be without an Imam and finally Imam knows everything which is needed for human being to get to the truth and goal.
What does the Quran verse 17:71 say?
A:
no age can be without an Imam