問題詳情

Passage 1 Laser The word laser was coined as an acronym for Light Amplification by the StimulatedEmission of Radiation. Ordinary light, from the Sun or a light bulb, is emitted spontaneously,when atoms or molecules get rid of excess energy by themselves, without any outsideintervention. Simulated emission is different because it occurs when an atom or moleculeholding onto excess energy has been stimulated to emit it as light.Albert Einstein was the first to suggest the existence of stimulated emission in a paperpublished in 1917. However, for many years, physicists thought that atoms and molecules alwayswere much more likely to emit light spontaneously and that stimulated emission thus alwayswould be much weaker. It was not until after the Second World War that physicists began tryingto make stimulated emission dominate. They sought ways by which one atom or molecule couldstimulate many others to emit light, amplifying it to much higher powers.The first to succeed was Charles H. Townes, then at Columbia University in New York.Instead of working with light, however, he worked with microwaves, which have a much longerwavelength, and built a device he called a “master,” for Microwave Amplification by theStimulated Emission of Radiation. Although he thought of the key idea in 1951, the first masterwas not completed until a couple of years later. Before long, many other physicists were buildingmasters and trying to discover how to produce stimulated emission at even shorter wavelengths.The key concepts for a laser emerged about 1957. Townes and Arthur Schawlow, then atBell Telephone Laboratories, wrote a long paper outlining the conditions needed to amplifystimulated emission of visible light waves. At about the same time, similar ideas crystallized inthe mind of Gordon Could, then a 37-year-old graduate student at Columbia, who wrote themdown in a series of notebooks. Townes and Schawlow published their ideas in a scientific journal,Physical Review Letters, but Could filed a patent application. Three decades later, people stillargue about who deserves the credit for the concept of the laser.
36. The word “coined” could be replaced by______ .
(A) created
(B) mentioned
(C) understood
(D) discovered

參考答案

答案：A
難度：適中0.461538
統計：A(6),B(3),C(2),D(1),E(0)

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