Three-dimensional but the physics is very much the same once you Imagine a one-dimensional system made of a long line ofĪtoms as shown in Fig. We want now to analyze quantitatively the quantum mechanical Position, it will later have moved to the other, and still later will On the other hand, if we start the electron in one Of the definite-energy states, the magnitudes of these two amplitudesĪre constant in time, and the phases vary in time with the sameįrequency. Each state can be described by the amplitudeįor the electron to be in each of the two basic positions. There are two possible states of definiteĮnergy for the electron. To go back, just as we have discussed for the hydrogen molecular ion Go from one position to the other, and, of course, the same amplitude Let’s also suppose that there is a certain amplitude to Two positions, in each of which it is in the same kind ofĮnvironment. Let’s now think of an electron which can be in either one of You will remember that we have discussed many examples of two-state The next one will describe the application of these principles in The machineryīehind the behavior of a transistor will be described in this chapter The transistor they move freely through a crystal lattice. In a radio tube electrons move freely through a vacuum, while in Instance, what makes it possible for a transistor to imitate the radio Permitted the development of many practical devices. This strangeįact is what lets metals conduct electricity so easily it has also Smoothly and easily-almost as if they were in a vacuum. Lattice is perfect, the electrons are able to travel through the crystal Nevertheless, it is a ubiquitous phenomenon of nature that if the You wouldĮxpect the electron to bump into one atom or another almost immediately. The order of a few angstroms-which is practically nothing. So that you would expect the mean free path between collisions to be of That is, the atoms are large, relative to their spacing, The effective diameter of the atom for electron scattering is roughly anĪngstrom or so. The atomsĪre packed together with their centers only a few angstroms apart, and Would have great difficulty passing through a solid crystal. You would, at first sight, think that a low-energy electron Mike The Feynman Lectures on Physics New Millennium Edition Your time and consideration are greatly appreciated. So, if you can, after enabling javascript, clearing the cache and disabling extensions, please open your browser's javascript console, load the page above, and if this generates any messages (particularly errors or warnings) on the console, then please make a copy (text or screenshot) of those messages and send them with the above-listed information to the email address given below.īy sending us information you will be helping not only yourself, but others who may be having similar problems accessing the online edition of The Feynman Lectures on Physics. This type of problem is rare, and there's a good chance it can be fixed if we have some clues about the cause.
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