College Physics

Landau level of silicene under a nonuniform magnetic field and a vertical electric field

. 2015, 34(11): 6-6.

Abstract ( 777 )

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Based on the elementary concepts of quantum mechanics and the special function theory, the Landau level spectrum in silieene under the combined effect of a nonuniform magnetic field and a vertical electric field is investigated. The results show that due to the spin-orbit coupling modulated by the electric field, there are some novel features in the Landau level structure of the system.

The magnetic fields on the axis of fractal coil

. 2015, 34(11): 8-8.

Abstract ( 692 )

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The magnetic moment area and magnetic field on the axis of generalized Koch and Hibert coil are calculated. Numerical results show that the magnetic moment area is exactly the real area.

Application of the magnetic mirror method based on conformal mapping

. 2015, 34(11): 11-11.

Abstract ( 876 )

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The two-dimensional static magnetic field boundary value problem of the complex shape boundary is solved by combing the magnetic mirror method and eonformal mapping method. Meanwhile, the distribution of mag- netic field is got. The magnetic induce line maps are plotted by using mathematical software MATLAB, thus the validity of the method in the paper is presented. The application range for magnetic mirror method is expanded, and a novel idea and way is provided for solving the complex shape boundary two-dimensional boundary value problem.

The energy levels of ＂W＂ type wells in electric field

. 2015, 34(11): 18-18.

Abstract ( 720 )

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Effects of electric field on energy levels in ＂W＂ type wells are investigated by using finite different method with Matlab language. The results show that the energy levels of system are affected by electric field. In an increasing electric field, the energy levels of ＂W＂ type system except the first levels are continuing to decline after an oscillating change, there is a more time in oscillation for the higher level. For two adjacent levels, the directions of oscillating change are opposite, and the interval tends to stable after oscillating change. These explain that the energy levels and intervals of ＂W＂ type wells can be controlled by electric field.

The proposition of Schwarzschild solution of gravitational field of spherical symmetry and analysis of black hole

. 2015, 34(11): 22-22.

Abstract ( 959 )

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The process of proposition of Schwarzschild solution of gravitational field of spherical symmetry is reviewed. The physical meaning of gravitational radius is illustrated. The development of concept of black hole is introduced. The non-strangeness of spherical space-time of gravitational radius and space-time structure in gravitational radius is analyzed.

Measurement of sound velocity based on sound card and MATLAB

. 2015, 34(11): 28-28.

Abstract ( 1106 )

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This paper designs a new method for measuring the sound velocity in the air, which is based on computer sound card and MATLAB software. The result shows that the design is correct, reliable, simple and sensitive.

Effects of two common misoperations on thermal conductivity measurement

. 2015, 34(11): 31-31.

Abstract ( 771 )

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Two common misoperations of stablestate method for thermal conductivity measurement are simulated. The effects of misoperations on thermal conductivity are investigated. Experimental results have shown that a misalignment of 5 ~ 10% between the sample and the plate causes 1.1 - 6.7% difference in thermal conductivity. The test with the steady temperature of 44 ℃ or 43 ℃ causes 35.8% and 45.3% difference in thermal conductivity, respectively. The changes in the temperature of radiating plate and the curvature of steady-state point, which are resul- ted from the misoperations, are identified as the origin for the changed thermal conductivity. The analysis of misopera- tion is good for optimizing the experimental method and serving the college experimental teaching.

Experiment design of interpreting principle of laser by measuring semiconductor gain spectrum

. 2015, 34(11): 35-35.

Abstract ( 867 )

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In this paper,physical principle of laser is interpreted by measuring semiconductor gain spectrum.A measurement applied to physical experiment is designed ,the relationship between two-sides amplified spontaneous emission （ASE） and net gain is educed, semiconductor is chosen as gain medium, and experiment setup that is easy to adjust and measure is used.The light ampliation caused by gain larger than loss in the system is shown by gain spectrum, while, the change of population inversion is expressed by gain in different pump current density.

Lawrence Bragg＇ s three Chinese students in Manchester --C. S. Cheng, S. S. Lu and S. H. Yii

. 2015, 34(11): 38-38.

Abstract ( 994 )

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C. S. Cheng, S. S. Lu and S. H. Yti were Chinese physicists, who all studied in UK from 1934 to 1936 at University of Manchester. Under the guidance of famous British physicist William Lawrence Bragg, the three students engaged in the research of X-ray crystallography. They made important achievements during their abroad. The academic achievements had a significant positive impact on their later research. They promoted the research about crystallography of China after they returned.

Application of the Jigsaw method in atomic physics class

. 2015, 34(11): 47-47.

Abstract ( 897 )

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Traditional oral teaching method which hinders student＇ s study enthusiasm and learning activity, fails to make effective connections between what is taught and what the students know. As a new interactive teaching method, the jigsaw cooperative learning which based on the jigsaw puzzle, is of very importance in stimulating the student＇ s learning activity, developing their creativity and critical thinking, as well as promoting team spirit. This paper offers a version of jigsaw method for enhancing knowledge of the Bohr model of hydrogen in atomic physics.

RC passive bandpass circuit and the method of error analysis

. 2015, 34(11): 53-53.

Abstract ( 1261 )

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This paper introduces the principle and the amplitude-frequency characteristic of the RC passive bandpass circuit, making a comparison in filtering effect between RLC passive bandpass circuit and it. Also, this paper provides a specific experiment, introduces a way to analyze the error of data and proves it.

Study of the blue light hazard of liquid crystal

. 2015, 34(11): 57-57.

Abstract ( 821 )

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Using the principle of grating spectroscopy, the harmful blue light is separated from the lights of liquid crystal display. By measuring the illumination value representing the damage of blue light, we provide a simplified method of evaluating the blue light hazard from the screen. Through the massive measurement of blue light hazard of liquid crystal on different conditions, some conclusions are drawn about the hazard. And some suggestions are raised that less liquid crystal should be used as well as used properly.

The university learning career of Max Born

. 2015, 34(11): 61-61.

Abstract ( 630 )

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Max Born was a great theoretical physicist in 20th century, but he had never wanted to be a physicist until he had prepared his PhD thesis. Then what specialized courses did he take in his university life？ What did he want to be at first？ At last what driven Born to become a physicist？ In all the process, were there anything which could give some inspirations to today＇ s teachers or students？ All the answers are presented in the paper.

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