College Physics

Albert Einstein and the birth of the general relativity ——The 100th anniversary of the theory of general relativity

. 2015, 34(12): 1-1.

Abstract ( 1061 )

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Introduces Einstein＇s great contribution in set up general relativity. He is the first one who discovers the equivalence principle and points out that gravitation is essentially a geometrical effect of curvature of space-time. Einstein is also the first person who gives the field equation which is the fundamental equation of general relativity. The three important experiments checking general relativity proposed by him have been proven by observation. Einstein is the sole founder of the theory of general relativity.

A new teaching method on uncertainty principle based on one-dimensional infinite potential well

. 2015, 34(12): 6-6.

Abstract ( 1150 )

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Heisenberg uncertainty principle is one of the difficult points in teaching on the college physics, because its derivation is difficult and goes beyond the content of college physics. The majority of teaching materials take single slit diffraction of a electron as an example and derives uncertainty principle in the coordinate and momentum. This teaching method is recipient and understandable. How ever it has also some disadvantages, which include inexactness in understanding uncertainty, helplessness for avoiding the classical concept on orbit, and so on. A new teaching method for this node is advised based on one-dimensional infinite potential well.

The nonlocal equivalent electromagnetic parameters of the metallic nanosphere particle

. 2015, 34(12): 9-9.

Abstract ( 721 )

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Based on the electromagnetic scattering theory and the equivalent principle for the electromagnetic scattering, we transform the metallic nanosphere particle with the permittivity properties including spatial dispersion （or nonlocal effect） into that in the local case without spatial dispersion, and further obtain the equivalent permittivity and permeability for the metallic nanosphere particle with spatial dispersion. Finally, with a concrete example, it is found that because of the existence of the longitudinal mode field inside the metallic nanosphere particle, there are the differences for the electromagnetic parameters between both above cases, which is especially obvious in the low-frequency region.

Fourier integral solution of Green function of Poisson equation

. 2015, 34(12): 14-14.

Abstract ( 1622 )

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The Green function of the Poisson equation is usually obtained from the Gauss＇ s theorem. Another way to get the Green function is presented by directly integrating its Fourier transformation expression. Appropriate regularization methods need to be chosen in the integration.A wrong regularization method is pointed out, while acorrect method is given.

The self-induction phenomena of the thin conductor loop in the uniform magnetic field

. 2015, 34(12): 16-16.

Abstract ( 915 )

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Using Faraday＇s law of electromagnetic electromotive force and the induced current on the static field which varies with time are solved. For the static thin induction and Kirchhoff＇s second law, the induced and revolving thin conductor loop in a uniform magnetic conductor loop, it is found that in every period, there are two time intervals, in which the induced electromotive force and the induced current take the opposite direction, and there are two time intervals, in which Lenz＇s law is false. With the circular frequency of the magnetic changes tending to infinity, the peak value of the induced electromotive force will tend to infinity, while the peak value of the induced current will tend to a constant. Only if the self-induction is ignored, the induced electromotive force and the induced current on the loop will satisfy Ohm＇s law. Finally, the magnetic field distribution in the plane which is enclosed by the thin conductor loop and the self-induction coefficient of the loop are analyzed.

Influence of a grounding conductor plate with straight slit on uniform electric field and its numerical simulation

. 2015, 34(12): 20-20.

Abstract ( 671 )

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The influence of a conductor plate with straight slit on uniform electric field is studied by using Schwarz-Christoffel transformation and its inverse transformation on the complex coordinate system of the complex number. Furthermore, the electric potential distribution and electric field intensity distribution are obtained. The electric field line maps are plotted using the software MATLAB. On extent of influence of a conductor plate with straight slit on uniform electric field is researched in qualitative.

Discussion on a problem about that the chronological order can be reversed or not in special theory of relativity teaching

. 2015, 34(12): 24-24.

Abstract ( 1481 )

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When students learn the relativity of simultaneity of special theory of relativity, they are easy to raise a question about the ideal experiment of the relativity of simultaneity. This essay raises this problem and uses the knowledge of time-like and space-like events to calculate and analyze it, and uses Miukowskian space to describe it geometrically to answer the question clearly and visually. Moreover, it makes a conclusion on judging the chronological order of events can be reversed or not.

Investigation on brachistochrone simulation experiment by Mathematica

. 2015, 34(12): 27-27.

Abstract ( 1034 )

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We design and accomplish the brachistochrone experiment. The experiment platform and simulate of the downslide process of ball are established. The simulation results are reasonable and the experimental process is intuitive. This courseware is convenient to the school teaching.

Automatic measurement and data processing of Franck-Hertz experiment

. 2015, 34(12): 31-31.

Abstract ( 2173 )

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A novel method for automatic measurement and data processing of Franck-Hertz experiment is presented. The software Origin is used for data processing and analyzing of the automatically measured data collected from a digital oscilloscope. Then the first excitation potential of argon atom is obtained. Compared with the manual measurement method, this automatic method can simplify the experimental procedure and improve the efficiency and accuracy of this experiment.

Analysis of transient process in LC serial circuit under condition of square wave input

. 2015, 34(12): 34-34.

Abstract ( 1480 )

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Differential equations of LC serial circuit under square wave excitation and the change rule of the continuous current and voltage of capacitance are analyzed, the every period transient function is deduced. The characteristic of functions is discussed. The analysis result is verified by Pspice.

Discussion on the innovative training and the critical thinking training --recommendation of the national excellent course and relevant thinking

. 2015, 34(12): 37-37.

Abstract ( 711 )

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The positive influence on the college student innovative training project is discussed. Hence werecommend the national excellent course and its textbook《The Critical Thinking in Science》 by professor BAO Jing-dong.

Improved and modularized circuital realization of Jerk system

. 2015, 34(12): 40-40.

Abstract ( 880 )

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This article analyzes the improved module based on Jerk system, and completes the circuital design for multi-scroll chaotic attractor. The simulation and circuits are used to prove the design experimentally. Compared with traditional modularized circuits, this circuit is much simpler and gets the results more precisely. One can change different chips or regulate the value of integrating resistor to observe the chaos, and change the frequency spectrum for practical applications.

Induced electromotive forces for various regions of magnetic field

. 2015, 34(12): 45-45.

Abstract ( 897 )

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In this paper, we calculate the electromotive forces produced by various regions of magnetic field. First, we discuss the electromotive forces in the case of finite long straight conductor. We calculate the electromotive forces for the circular, rectangular and triangular shapes of magnetic field and get analytic results. We find that the results depend on the shapes of the magnetic field and the size of the conductor. Second, we discuss the electromo- tive forces for the case of infinite conductor. In this case, we prove that the electromotive forces only depend on the cross-sectional area of magnetic field. The results are independent of the shapes of magnetic field and the distance from the magnetic to the conductor.

The photoelectric effect and electrical properties derived from moving electrified metal plate

. 2015, 34(12): 50-50.

Abstract ( 763 )

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This is the first time to combine the photoelectric effect and electrical properties derived from moving electrified metal plate. It is concluded that the voltage between the movement of charged metal plates becomes smaller, the electric field intensity is constant, the capacitance increases.

Will the pressure from a laser pointer be harmful to human eyes or not？

. 2015, 34(12): 52-52.

Abstract ( 1235 )

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When giving presentations, many people use a laser pointer to direct the attention of the audience to information on a screen. The primary properties of laser light that make it useful in these technological applications are these ： high intensity and a small angle of divergence. In this paper, using laser light radiate pressure, the pres- sure from laser pointer is derived and analyzed. The result shows that even for the radiated pressure from a 3.0-mW laser pointer is about the same as that of sunlight at the Earth＇ s surface. For this reason, it is not safe to shine the beam of a laser pointer into a person＇ s eyes, which may be more dangerous than looking directly at the Sun.

Cooperation between Max Born and von Karman

. 2015, 34(12): 56-56.

Abstract ( 878 )

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After Max Born became the lecturer in Gottingen, he met another lecturer, von Karman, who was little older than Max Born, they became good friends, and started to study specific heat of solid by crystal model together. In Born＇s mind, the research cooperated with Karman had a special meaning to his scientific career. Based on the recollections of Born, Karman and Richard Courant who knew them well. This paper discusses the respective role they had made in the research work, and also discusses why they ended the cooperation so soon. Some details of Born＇s scientific career in his lecturer period have been shown.

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