The left diagram in FIGURE 10.1 might represent a two atom crystal with two bands. Basing your argument on the kinetic energy inside either individual well, explain why both energies in the lower band should be roughly equal to that of the atomic state and why both energies in the upper should roughly equal that of the atomic state
Both energies in the lower band should be roughly equal to that of atomic state because the two atomic states have the same kinetic energy, the linear combination of these states will also have the same energy as of state.
For an individual well, the kinetic energy of an electron for atomic state or atomic state is a fixed number. When there are two wells, there are two atomic states at or .
An electron at molecular state has large separation, and so converges to the addition or subtraction of the two atomic states. Since the two atomic states have the same kinetic energy, the linear combination of these two states will also have the same energy as that of atomic state.
Hence, an electron at molecular state has small separation, and so the energy of the molecular state is only roughly equal to energy for atomic state.
Question: Volumes have been written on transistor biasing, but Figure 10.45 gets at the main idea. Suppose that and that the "input" produces its own voltage . The total resistance is in the input loop, which goes clockwise from the emitter through the various components to the base, then back to the emitter through the base-emitter diode. this diode is forward biased with the base at all times 0.7 V higher than the emitter. Suppose also that Vcc = 12 V and that the "out- put" is . Now. given that for every 201 electrons entering the emitter, I passes out the base and 200 out the collector, calculate the maximum and minimum in the sinusoidally varying
(a) Current in the base emitter circuit.
(b) Power delivered by the input.
(c) Power delivered to the output.
(d) Power delivered by Vce.
(e) what does most of the work.
In diamond, carbon’s four full (bonding) s and p spatial states become a band and the four empty(anti bonding) ones becomes a higher energy band. Considering the trend in the band gaps of diamond, silicon, and germanium, explain why it might not be surprising that “covalent” tin behaves as a conducting metallic solid.
The diagram shows an idealization of the "floating magnet trick" of Figure 10.50. Before it is cooled, the superconducting disk on the bottom supports the small permanent magnet simply by contact. After cooling, the magnet floats. Make a sketch, showing what newmagnetic fields arse. Where are the currents that produce them?
Question: In Chapter 4. we learned that the uncertainty principle is a powerful tool. Here we use it to estimate the size of a Cooper pair from its binding energy. Due to their phonon-borne attraction, each electron in a pair (if not the pair's center of mass) has changing momentum and kinetic energy. Simple differentiation will relate uncertainty in kinetic energy to uncertainty in momentum, and a rough numerical measure of the uncertainty in the kinetic energy is the Cooper-pair binding energy. Obtain a rough estimate of the physical extent of the electron's (unknown!) wave function. In addition to the binding energy, you will need to know the Fermi energy. (As noted in Section 10.9, each electron in the pair has an energy of about EF.) Use 10-3 eV and 9.4 eV, respectively, values appropriate for indium.
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