课程名称︰普通物理学甲下 课程性质︰系定必修 课程教师︰高涌泉 开课学院：理学院 开课系所︰物理系 考试日期（年月日）︰2011/6/21 考试时限（分钟）：100分钟 是否需发放奖励金：是 （如未明确表示，则不予发放） 试题 : 1.(a)(10%)It is said that the laws of electrodynamics are inconsistent without the displacement current. Explain why. (b)(10%)Consider the RC circuit shown in Fig.1. Switch S is closed at time t=0. Calculate the displacement current in the capacitor as a funtion of time. R ┌───／＼／＼／───┐ │ │ │ ╲ ─┴─ S C ─┬─ │ │ │ │ │ │ └─────┤├────┘ │ ε Fig.1. (c)(10%)Consider Fig.1. again. This time the switch is closed. At some time, the switch is opened. What is the displacement current. 2.(10%)Consider an RLC circuit. The energy is given by 2 2 LI Q E = ── + ── . 2 2C Show that the rate of change of this energy is equal to the power loss in the resistor( the ohmic heating power). 3.(10%)Consider a standing EM wave for which the electric field is → ^ E = E sin(kx)cos(ωt) j . 0 (a)What is the magnetic field? (b)What is the Poynting vector? 4.(25%)Explain the following: (a)Bohr magneton (b)Paramagnetism (c)Meissner effect (d)Dipole radiation (e)Malus's law 5.(15%)It was argued in the class that if a quantum particle is to be cofined in a potential well, the particle must have a very definite energy (eigen energy) What is the argument? 6.(10%)Seven electrons are in an infintely deep 1-dimensional potential well of width L. (a)What is the lowest possible energy for this system? (b)What is the next highest energy value? (In both parts, ignore Coulomb interations between r=the electrons.) --

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