Final Examination of Physics II for 2009 Mixed Class普通物理

浙江大学2010-2011学年 秋冬 学期

《 普通物理学 II》课程期末考试试卷

课程号：__理学院___

考试试卷：√A卷、B卷（请在选定项上打√）

考试形式：√闭、开卷（请在选定项上打√），允许带_计算器_入场

考试日期： 2011 年 01 月 17 日,考试时间： 120 分钟

诚信考试，沉着应考，杜绝违纪。

考生姓名： 学号： 所属院系： _

00e，

h=6.63 10-34J·s

I. Fill in the space underlined. (35%)

1. Figure 1 shows a Thomson atom model of helium (He, Z=2). Two electrons, at rest, are embedded inside a uniform sphere of positive charge 2e. The distance d between the electrons is so that the configuration is in static equilibrium.

2. Two long wires a distance b apart carry antiparallel currents i, as in Figure 2. The magnetic induction strength B at point P, which is equidistant from the wires, is given by .

3. For the charge configuration of Figure 3, the electric potential V(r) for points on the vertical axis, assuming r>>d is given by . Set V=0 at infinity.

4. A broad source of light ( =680nm) illuminates normally two glass plates 120mm long that touch at one end and are separated by a wire 0.048mm in diameter at the other end (Fig. 4). How many bright fringes appear over the 120-mm distance? 5．What would be the action of a quarter-wave plate ( /4波片)on the linearly polarized (assume the plane of vibration to be at 45o

6. The de Broglie’s wavelength of a 1.00-KeV electron is of 7. Stationary state Schrödinger’s Equation(定态薛定谔方程) for one dimensional system is:

II. Multiple Choice (Choose all the apply, 20%)

1. Which of the following does not significantly contribute to the magnetic properties of a substance?

(A) Orbital magnetic moments of electrons. (B) Spin magnetic moments of electrons

(C) Magnetic moments of protons and neutrons. (D) All contribute equally.

2. Two ideal polarizing sheets are stacked so that none of the incident unpolarized light is transmitted. A third polarizing sheet is slipped between the first two sheets at an angle of 45o to the bottom sheet. The fraction of light transmitted through the entire stack is:

(A) 1/2 (B) 1/4 (C) 1/8 (D) Still zero

3. The diffraction pattern of a single slit is observed with green light. The green light is then replaced by red light. Which of the following changes will allow the locations of the diffraction minima on the screen to remain unaffected by the change of light color?

(A) Increase the width of the slit. (B) Decrease the width of the slit.

(C) Move the lens-screen combination way from the slit. (D) Increase the intensity of the light source.

4. A beam of electrons with speed v0 pass through double slits and then is allowed to strike a fluorescent screen. An interference pattern is observed on the screen. The speed of the electrons is increased to 2v0. What happens to the spacing of the interference fringes on the screen?

(A) The spacing increases. (B) The spacing decreases

(C) The spacing remains the same. (D) The interference fringes disappear.

III. Problems (present the necessary equations in solution) (45%)

1. (8%) Please write out:

(a) The image formation equation for the spherical refracting surface with paraxial rays. (b) The properties of electromagnetic wave at distance from a wave source.

2. (8%) A grating has 104rulings/cm and is 10cm wide. A light with =4500 is incident on

the grating.

(a) How many higher orders can be seen?

(b) What the smallest wavelength interval that can be resolved in the highest order?

3. (15%) Figure 5 shows a parallel-plate capacitor being charged. The voltage across the

plates has a time dependence V=V0cos t. The fringing of the electric field and radiation can be ignored.

(a) To determine the electric and magnetic field in the region between plates as a function of time t.

(b) How large does the current flow in the wires and what is the time dependence of the current density between the plates?

(c) Write the Poynting vector S at the edge of the capacitor (including its magnitude and

direction).

4. (14%) As shown in Figure 6, the surface charge density of a parallel-plate capacitor is of

0 (constant), the distance between two plates is of d, the space is filled with an isotropic but non-uniform (各向同性,但非均匀) dielectric. The polarization coefficient (极化率) of the dielectric is e(x)= 0(1+ x), where 0， are constants. Calculate the volume charge density ’(x) of the induced charge (束缚电荷) in the dielectric; the surface charge density ’(0), ’(d) of the induced charge on both surface of the dielectric.