{"id":8394,"date":"2022-06-10T05:59:21","date_gmt":"2022-06-10T05:59:21","guid":{"rendered":"https:\/\/www.booksofall.com\/es\/?post_type=product&p=8394"},"modified":"2022-06-10T05:59:21","modified_gmt":"2022-06-10T05:59:21","slug":"university-physics-volume-3","status":"publish","type":"product","link":"https:\/\/www.booksofall.com\/es\/university-physics-volume-3\/","title":{"rendered":"University Physics Volume 3"},"content":{"rendered":"

University Physics<\/i>\u00a0is a three-volume collection that meets the scope and sequence requirements for two- and three-semester calculus-based physics courses.\u00a0Volume 1<\/i><\/a>\u00a0covers mechanics, sound, oscillations, and waves.\u00a0Volume 2<\/i><\/a>\u00a0covers thermodynamics, electricity, and magnetism, and\u00a0Volume 3<\/i>\u00a0covers optics and modern physics. This textbook emphasizes connections between theory and application, making physics concepts interesting and accessible to students while maintaining the mathematical rigor inherent in the subject. Frequent, strong examples focus on how to approach a problem, how to work with the equations, and how to check and generalize the result.<\/p>\n

Our investigation of light revolves around two questions of fundamental importance: (1) What is the nature of light, and (2) how does light behave under various circumstances? Answers to these questions can be found in Maxwell\u2019s equations (in Electromagnetic Waves), which predict the existence of electromagnetic waves and their behavior. Examples of light include radio and infrared waves, visible light, ultraviolet radiation, and X-rays. Interestingly, not all light phenomena can be explained by Maxwell\u2019s theory.<\/p>\n

Experiments performed early in the twentieth century showed that light has corpuscular, or particle-like, properties. The idea that light can display both wave and particle characteristics is called wave-particle duality, which is examined in Photons and Matter Waves.<\/p>\n

In this chapter, we study the basic properties of light. In the next few chapters, we investigate the behavior of light when it interacts with optical devices such as mirrors, lenses, and apertures.<\/p>\n

The Propagation of Light<\/h4>\n

Learning Objectives<\/strong>
\nBy the end of this section, you will be able to:
\n\u2022 Determine the index of refraction, given the speed of light in a medium
\n\u2022 List the ways in which light travels from a source to another location<\/p>\n

The speed of light in a vacuum c is one of the fundamental constants of physics. As you will see when you reach Relativity, it is a central concept in Einstein\u2019s theory of relativity. As the accuracy of the measurements of the speed of light improved, it was found that different observers, even those moving at large velocities with respect to each other, measure the same value for the speed of light. However, the speed of light does vary in a precise manner with the material it traverses. These facts have far-reaching implications, as we will see in later chapters.<\/p>\n

The speed of light in a\u00a0vacuum<\/a>\u00a0is defined to be exactly 299 792 458\u00a0m\/s<\/a>\u00a0(approx. 186,282 miles per second). The fixed value of the speed of light in SI units results from the fact that the metre is now defined in terms of the speed of light. All forms of electromagnetic radiation move at exactly this same speed in vacuum.<\/p>\n

Different\u00a0physicists<\/a>\u00a0have attempted to measure the speed of light throughout history.\u00a0Galileo<\/a>\u00a0attempted to measure the speed of light in the seventeenth century. An early experiment to measure the speed of light was conducted by\u00a0Ole R\u00f8mer<\/a>, a Danish physicist, in 1676. Using a\u00a0telescope<\/a>, R\u00f8mer observed the motions of\u00a0Jupiter<\/a>\u00a0and one of its\u00a0moons<\/a>,\u00a0Io<\/a>. Noting discrepancies in the apparent period of Io’s orbit, he calculated that light takes about 22 minutes to traverse the diameter of Earth’s orbit. <\/sup>However, its size was not known at that time. If R\u00f8mer had known the diameter of the Earth’s orbit, he would have calculated a speed of 227 000 000\u00a0m\/s.<\/p>\n

Another more accurate measurement of the speed of light was performed in Europe by\u00a0Hippolyte Fizeau<\/a> in 1849.\u00a0<\/sup>Fizeau directed a beam of light at a mirror several kilometers away. A rotating\u00a0cog wheel<\/a>\u00a0was placed in the path of the light beam as it traveled from the source, to the mirror and then returned to its origin. Fizeau found that at a certain rate of rotation, the beam would pass through one gap in the wheel on the way out and the next gap on the way back. Knowing the distance to the mirror, the number of teeth on the wheel and the rate of rotation, Fizeau was able to calculate the speed of light as 313 000 000\u00a0m\/s.<\/p>\n

L\u00e9on Foucault<\/a>\u00a0carried out an experiment which used rotating mirrors to obtain a value of 298 000 000\u00a0m\/s<\/sup>\u00a0in 1862.\u00a0Albert A. Michelson<\/a>\u00a0conducted experiments on the speed of light from 1877 until his death in 1931. He refined Foucault’s methods in 1926 using improved rotating mirrors to measure the time it took light to make a round trip from\u00a0Mount Wilson<\/a>\u00a0to\u00a0Mount San Antonio<\/a>\u00a0in California. The precise measurements yielded a speed of 299 796 000\u00a0m\/s.<\/sup><\/p>\n

The effective velocity of light in various transparent substances containing ordinary\u00a0matter<\/a>, is less than in vacuum. For example, the speed of light in water is about 3\/4 of that in vacuum.<\/p>\n

Two independent teams of physicists were said to bring light to a “complete standstill” by passing it through a\u00a0Bose\u2013Einstein condensate<\/a>\u00a0of the element\u00a0rubidium<\/a>, one team at\u00a0Harvard University<\/a>\u00a0and the\u00a0Rowland Institute for Science<\/a>\u00a0in Cambridge, Massachusetts and the other at the\u00a0Harvard\u2013Smithsonian Center for Astrophysics<\/a>, also in Cambridge. <\/sup>However, the popular description of light being “stopped” in these experiments refers only to light being stored in the excited states of atoms, then re-emitted at an arbitrary later time, as stimulated by a second laser pulse. During the time it had “stopped” it had ceased to be light.<\/p>\n","protected":false},"excerpt":{"rendered":"