2. 职称英语
  3. The word "laser" was coined as an acronym for Light Amplification by the Sti

The word "laser" was coined as an acronym for Light Amplification by the Sti

游客2023-09-13  33
问题     The word "laser" was coined as an acronym for Light Amplification by the Stimulated Emission of Radiation. Ordinary light, from the Sun of a light bulb, is emitted spontaneously, when atoms or molecules get rid of excess energy by themselves, without any outside intervention. Stimulated emission is different because it occurs when an atom of molecules holding 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 paper published in 1917. However, for many years physicists thought that atoms and molecules always were much more likely to emit light spontaneously and that stimulated emission thus always would be much weaker. It was not until after the Second World War that physicists began trying to make stimulated emission dominate. They sought ways by which one atom or molecule could stimulate 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 longer wavelength, and built a device he called a "maser", for Microwave Amplification by the Stimulated Emission of Radiation. Although he thought of the key idea in 1951, the first maser was not completed until a couple of years later. Before long, many other physicists were building masers and trying to discover how to produce stimulated emission at even shorter wavelengths.
    The key concepts emerged about 1957. Townes and Arthur Schawlow, at Bell Telephone Laboratories, wrote a long paper outlining the conditions needed to amplify stimulated emission of visible light waves. At about the same time, similar ideas crystallized in the mind of Gordon Gould, then a 37-year-old graduate student at Columbia, who wrote them down in a series of notebooks. Townes and Schawlow published their ideas in a scientific journal, Physical Review Letter, but Gould fried a patent application. Three decades later, people still argue about who deserves the credit for the concept of the laser. [br] In this research at Columbia University, Charles Townes worked with ______.
选项 A、stimulated emission
B、microwaves
C、maser
D、stimulated emission and microwaves
答案 D
解析 事实细节题。在文章第三段第一句，从maser一词所代表的意思得到解释，它是microwaves Amplification by the stimulated Emission of Radiation，其中A“刺激释放”和B“微波”都涉及到了，所以 D为最佳答案。C为“微波激射器”。Townes本身研究的就是maser，但maser并不是Townes在哥伦比亚期间的制作，他是制作maser所涉及的刺激释放和微波，故C是错的，在做这个题时，要对题干理解清楚，才不会误选C。
转载请注明原文地址:https://tihaiku.com/zcyy/3011664.html
相关试题推荐
随机试题
最新回复(0)