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自然科學 大學

求解答案是否正確

Multiple-choice questions: (70 points) write the letter of statement that is not true: 1. A.B.U The Drude Model: (a) It is a classical approach using concepts from the kinetic theory of gases. (b) A relaxation-time approximation is used where the probability of collision is l/t. (c) No forces act on the electrons in between collisions. (d) It predicts accurately the electronic heat capacity of metals. 2. The Sommerfeld Model: (a) The crystal potential is replaced by an average Coulomb potential. (b) The separation of states is so close that a continuum model can be applied. (c) The electrons are highly localized due to a strong crystal potential. (Q) The energy of the highest occupied state at 0 K is the Fermi energy. 3. Density of states in k-space, N(k): (a) N(k) is determined by the boundary value conditions. (b) For lattices in any dimensions, N(k) is constant in k-space. (C) N(k) depends on the direction and magnitude of k. (d) It is directly proportional to the volume of the crystal. E影響, c 4. The Fermi surface of a metal: (a) is responsible for many of the transport properties of the metal, (b) depends on the nature of the chemical bonds, (c) is always a sphere, (d) can involve mixing of electron orbitals. ✓ 5. The conductivity of a material () increases with the mobility of its carriers, (b) increases with the density of carriers, (C) it is inversely proportional to the energy gap. cogu changes with temperature. 6. BID Plasmons: (a) They are an important characteristic of the Sommerfeld electron gas model. (b) Plasmons occur spontaneously in metals. (c) They are related to charge density oscillations. (d) The Plasmon energy is typically of the order of 10 eV. The Fermi energy Ef in intrinsic semiconductors 8) is usually close to y E, at OK (b) it ACiD. can increase or decrease with temperature depending on the ratio of hole and electron effective masses, (c) it represents the point at which the probability of occupation is 12, even though there may not been any states with that energy, (d) its value relative to the electronic bands must remain unaffected in the presence of defects or interfaces.

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自然科學 大學

請問第七題怎麼解

60 s, turn 90 20 km/h for 2.0 min, turn 90° to the point, (a) how far are you from your starting point, and what direction relative to your initial direction of travel are you? V During volcanic eruptions, chunks of solid rock can be blasted out of the volcano; these projectiles are called volcanic bombs. Figure 4-22 shows a cross section of Mt. Fuji, in Japan. (a) At what initial speed would a bomb have to be ejected, at angle 0o = 60.0° to the horizontal, from the vent at A in order to fall at the foot of the volcano at B, at vertical distance h = 2.60 km and horizontal distance d = 9.40 km? Ignore, for the moment, the effects of air on the bomb's travel. (b) What would be the time of flight? (c) Would the effect of the air increase or decrease your answer in (a)?onatlar slow orl w moito Movisio Olovo vibolov te tootsodio dos olvistatani se moltotib nur no vodo as vd botu 29 vd baidot otsi Nomstl moll bottom 12 A plane flies 5 then 1100 km sout) trip, what are the displacement, the velocity, and (e) is 13 An astronau of 4.5 m. (a) Wha eration has a ma minute are requ period of the m 14 A basebal mum height al after reaching that is 86.0 m (a) What may ball? (b) How the ball strike blitt 00 Troede Vibolov sister sam 12 d B 15 The ran also on the place to plac broad jump (where g= by how mu instead in 1 Figure 4-22 Problem 7. 8 Oasis A is 90 km due west of oasis B. A desert camel leaves A and takes 55 h to walk 75 km at 37° north of due east. Next it takes 45 h to walk 65 km due south. Then it rests for 5.0 h. What are the (G) magnitu Cia

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自然科學 大學

大一普化 5.36求解

5.38 9389 信4 5,42 sphere (about 30 Where the temperatu lbove the surface of Earth), >and presSure are 一235C : h gd 交 and 3.00 XX 10 atm, respectively. Calculate the final Volume of the balloon. The temperature ot 2.5 L of a gas initially at SUN increased to 2507”C at constant volume. Calculate the final pressure of the gas in atm. The pressure of 6.0 L of an ideal gas in aflexible contalner 1S decreased to one-third of its original presSure, and 1ts absolute temperature 1s decreased by one-half. What 1s the flnal volume of the gas? A gas evolved during the tfermentation of glucose (wine making) has a volume of 0.78 L when mea- sured at 20.1?C and 1.00 atm. What was the volume of this gas at the fermentation temperature of 36.5 C and 1.00 atm presSure? An ideal gas originally at 0.85 atm and 66”C was allowed to expand until its final Volume, preSSure, and temperature were 94 mL, 0.60 atm, and 45 C, respectively. What was its initial volume? The volume of a gas at STP is 488 mL. Calculate 1ts volume at 22.5 atm and 1507C. A gas at 772 mmHg and 35.0”C Qceuples a Volume of 6.85工. Calculate its volume at STEP. Dry ice is solid carbon dioxide. A 0.050-g sample ot dry ice js placed in an evacuated 4.6-L vessel at 30。C. Caleulate the pressure inside the VesSel after all the dry ice has been conVerted to CO gasS, Avolume of 0.280Lofagas at STP weighs 0.400 g. Calculate the molar mass Of the gas. Aquantity of gas Weighing 7.10g at741tor and 445C oeeupies a volume of 5.40L. What is its molar mass? Si人2 5.93 5.54 Dalt 和Ae0U76 5 5.56

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