College Physics Test（B）(July,2009) 适用对象：2007级药学（英语）专业及2008级基础药学理科基地班 专业 级 班 姓名 学号
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І. Put correct answer into the following blank. （2 scores for each blank, total score: 20） 1.The rod carries a uniformly distributed charge Q .Determine the potential V(y) for points along the y (y>0) axis outside the rod . （1） 2.A uniform rod of mass M and length l can pivot freely (i.e., we ignore friction) about a hinge which is at the end of rod. The rod is held horizontally and then relead. At the moment of relea, the linear acceleration of the tip of the rod （2） . Determine the angular velocity of the rod when it reaches the vertial position. （3） 3. A parallel-plate capacitor has fixed charges +Q and –Q. The paration of the plates is then doubled. (a)By what factor does the energy stored in the electric field change? （4） ;(b)How much work must be done if the paration of the plates is doubled from d to 2d? （5） (The area of each plate is A) 4.The graph of displacement versus time for a small mass at the end of spring is shown in figure. At t=0 ,x=0.43cm .Write the equation for displacement x as a function of time.(6) 5. A ction of an infinitely long cylindrical rod with a uniform +. Let us find an expression for the magnitude of the electric field at a distance r from the axis of the rod.(7) 6. Red light illuminates a double-slit system with d=0.2mm. The first-order maximum occurs at x=3.3mm on a screen 1.0m from the slits. What is the wavelength of red light? (8) 7.A puddle of water has a thin film of gasoline floating on it. A beam of light is shining perpendicular on the film. If the wavelength of light incident on the film is 560 nm and the indices of refraction of gasoline and water are 1.40 and 1.33, respectively, what is the minimum thickness of the film to e a bright reflection? (9) 8. A very fine thread is placed between two glass plates on one side and the other side is touching to form a wedge. A beam of monochromatic light of wavelength 600 nm illuminates the wedge and 15 bright fringes are obrved. What is the thickness of the thread? (10) ．Choo the best answer to complete each of the following question. (fill in the blank form with correct answers) （1 score for each question, total score: 10）
1. A uniform thin rod of mass M (M=1kg) and length L (L=0.6m) is suspended vertically from frictionless pivot freely at its upper end .And the rod is still at first. A mass m (m =0.01g) of bullet traveling horizontally with a speed v1(v1=500m/s) strikes the rod at the distance l (l=0.36m) to the axis and with a speed v2 (v2=200m/s) passing through rod .What is angular speed of the rod? (a) 0.018rad/s (b) 0.27 rad/s (c) 0.09rad/s (d) 0.009 rad/s 2. A simple harmonic oscillator is undergoing oscillations with an amplitude A. How far is it from its equilibrium position when the kinetic and potential energies are equal? (a) (b) 2A 2016年12月(c) (d)A/2 3. A capacitor consists of a t of two parallel plates of area A parated by a distance d. This capacitor is connected to a battery and charged until its plates carry charges +Q and -Q. If the paration between the plates is doubled, the electrical energy stored in the capacitor will (a) double. (b) quadruple. (c) be cut in half. (d) be cut in fourth. 4. A double-slit interference experiment is performed in the air. Later, the same apparatus is immerd in benzene (index of refraction, n = 1.50), and the experiment is repeated. When the apparatus is in benzene, you obrve the interference fringes to be 牙齿怕冷(a) more cloly spaced as when the apparatus is in air. (b) equally spaced as when the apparatus is in air. (c) more widely spaced as when the apparatus is in air. (d) impossible to tell without knowing the wavelength of light in u. 5. A slit 1.00 mm wide is illuminated by light of = 589 nm. We e a diffraction pattern on a screen 3.00 m away. What is the distance between the first two diffraction minima on the same side of central diffraction maximum? (a) 2.77 mm (b) 0.27mm (c)1.77 mm (d) 0.77 mm 6. What is Brewster’s angle for the light is coming from water to air?( water who index of refraction is n=1.33 ) (a) 57.3˚ (b) 36.9˚ (c) 48.8˚ (d) 53.1˚ 7. The X-rays are directed at a crystal who atoms, lying in planes, are spaced 0.245nm apart. The cond diffraction maximum is recorded at 23.4˚. what is wavelength (a) 0.0486nm (b) 0.0973 nm (c) 0.0937 nm (d) 0. 973 nm 8. In a single-slit diffraction experiment, a beam of monochromatic light of wavelength 550 nm is incident on a slit of width 3.5 µm. If the distance between the slit and the screen is 10.0 m, how far is the first diffraction from the central maximum 现场5s? (a)0.0236m (b) 2.36m (c)0.168m (d) 0.236m 9. How far away can a human eye distinguish two car headlights 2.0 m apart ? Consider only diffraction effects and assume an eye diameter of 5.0 mm and a wavelength the of 500nm? (a)8 km (b) 16 km (c)24 km (d) 32 km 10. The concentration of compound solution of drag is 0.75g/cm3 and the specific rotation is 6.20cm3/(g.dm) at 20℃, using a 20-cm sample tube and sodium lamp for the measurement. What is an optical rotation of this drag (a) 9.3° (b) 93° (c) -9.3° (d) -93° ．Decide whether the following statements are true or fal (T/F) (fill in the blank form with correct answers) ( 1 score for each question, total score: 10）
1. Rotational inertia is determined by the total mass and the distribution of mass to the axis, but rotational inertia relative to different axis is same . 2. Polarization of light proofs that light is transver wave. 3. In general, the light path is greater than the path of light pass. 4. In the experiment for interference using the concept of air wedge , the point where the glass plates touch in an air wedge is a dark fringe. 5. Density of electric energy is proportional to the square of electric field. So the more the electric field, the less is the energy of electric field. 6. Waves carry energy from space to space without matter being carried. Intensity is proportional to the square of amplitude. 7. Effects of dielectrics polarizing generates polarization charges and polarization field within medium . So the effect of dielectric is to strengthen the original electric field. 8. In a single-slit diffraction experiment, the central maximum is broadened if the wavelength of light incread. 9. The direction of the electric field at a location just outside a conductor is perpendicular to surface of the conductor. 10. A standing wave is not wave since it does not move (lost the feature of waves). It has a certain wave-pattern. . Calculation 1. (total score: 10) A uniform thin rod of mass M and length l is suspended vertically from frictionless pivot freely at its upper end . And the rod is still at first. A mass m traveling horizontally with a speed v0 strikes the end of rod and stick in it. What is the 奖学金申请理由angular momentum of the rod after striking ? (10 scores) 2. a 3. 2. (total score: 10) In Young’s exp. monochromatic light of wavelength 550 nm falls on slits. If one of slits is covered up by a media layer (n=1.58), the original central bright fringe will move to the position of 7-order bright fringe, what is the thickness of the layer? (10 scores) 3. (total score: 10)A particle is in SHM along x axis, the amplitude A=0.06m, the period T=2s. When initial time t = 0, a particle is at positive maximum displacement x0= 0.06m. (1) Try to find the expression of this SHM; (3 scores) (2) When this oscillation moves along positive x direction with velocity v=2m/s and equilibrium of the particle is at displacement x0=0m . Try to find the expression of this SHW; (4 scores) (3) Try to find out wavelength of the SHW. (3 scores) 4. (total score: 10)Light of wavelength 600nm incident normally on a diffraction grating. The 2th-order bright fringe occurs at angle given by sin =0.20, and the 5th-order maxima are missing. Calculate (a) What is the paration between adjacent slits? (3 scores) (b) What is the slit-width of this grating? (2 scores) (c) How many orders of intensity maxima can be obrved by this grating, what are they? (5 scores) 5. (total score: 10)A conducting sphere with positive chargeｑradius R1，surrounded by a conducting shell without charge originally，inner radius R2 and external radius R3.The dielectric material of dielectric constant k fills all the space between the sphere and the shell. Find (1) electric field in space? (3 scores) （2）potential of inner sphere U1？(3 scores) （3）bound charge per unit area in the surface with inner radius R2 (1 score) （4）what is the electric energy in the dielectric space? (3 scores) 6. (total score: 5)Using air-wedge to test if a workpiece is flat and get interference pattern as the Fig. shown. Monochromatic incident light of wavelength is .Find the dimension of the flaw. ()争长论短(5 scores) 7. (total score: 5)Unpolarized light pass through two polaroids ; the axis of one is vertical and that of the other is at 60˚ to the vertical .The intensity of the transmitted light is. And now put the third polariod sheet between the two polaroids . Unpolarized light pass though three successive each of who axis makes 30˚ angle with the previous one in clockwi orientation. What is the intensity of the transmitted beam? (5 scores) | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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