Top Read Articles

Published in last 1 year |

In last 2 years |

In last 3 years |

All

Please wait a minute...


For Selected: Download Citations EndNote Ris BibTeX Toggle Thumbnails

Select

Application of measurement uncertainty analysis in university physics experiments — gravity acceleration measured by single-swing ZHANG Zhu li, CHEN Xin lei, LU Mei hong College Physics    2022, 41 (2): 31-.   DOI: 10.16854/j.cnki.1000-0712.200521 Abstract （8945）      PDF（pc） （826KB）（1360）       Knowledge map    Save Gravity acceleration is an important mechanical constant in physics. There are many methods to measure the value of gravity acceleration, and the simple pendulum method is often used in university physics experiments. However, the experimental principle only studies the motion of the single pendulum ball and ignores the influence of the size of pendulum, buoyancy, cycloid mass and other factors, so the measurement results are not accurate enough. The relative accurate formula of gravity acceleration and the corresponding synthetic standard uncertainty formula are obtained by correcting the system error that caused in the measurement of gravity acceleration by the simple pendulum method. Finally, the measured data are analyzed and calculated reasonably, and the more accurate experimental results are obtained. Related Articles | Metrics | Comments（0）

Select

Condition of half-wave loss when light is emitted from optically  denser medium to optically thinner medium QIU Hui-bin, WU Jun-jie, XIAO Dong-hua, HU Tian-yi, ZHONG Cheng-jie, LI Xiao-bin College Physics    2022, 41 (6): 40-.   DOI: 10.16854/j.cnki.1000-0712.210465 Abstract （3831）      PDF（pc） （475KB）（815）       Knowledge map    Save Through detailed derivation, graph presentation and discussion of the ratio relationship between the amplitude of the reflected wave and that of the incident wave, this article gives the detailed distribution map of phase difference between the reflected light and the incident light in the refractive index-incident angle space. At the same time, various conditions for the occurrence of half-wave loss are specified, including the half-wave loss of the reflected light when the light is emitted from the optically denser medium to the optically thinner medium. Here we show that when the light beam is shot from the optically denser medium to the optically thinner medium, the reflected wave may also occur half-wave loss; when the light beam is shot from the optically thinner medium to the optically denser medium, the reflected wave does not necessarily occur a half-wave loss. Our work clarifies and supplements some unclear conclusions in existing textbooks. Related Articles | Metrics | Comments（0）

Select

Dirac δ-function and its related applications ZHENG Shen-zhou, KANG Xiu-ying College Physics    2021, 40 (7): 25-.   DOI: 10.16854 /j.cnki.1000-0712.200456 Abstract （3758）      PDF（pc） （299KB）（735）       Knowledge map    Save It is indicated that Dirac δ-function is a continuation of the discrete Kronecker δ-function，which plays an important role in both mathematics and physics. In this paper，the precise definition of Dirac δ-function is introduced based on the concept of generalized functions，and it is proved that the Dirac δ-function is not a usual function in the Lebesgue sense of local integrable one. To this end，the Dirac δ-function is here approximated in the sense of weak limit by making use of the sequences of the unit rectangle impulse functions，Gauss functions，Bell- shaped functions and Sinc-functions，respectively. In addition，it is checked that the Dirac δ-function is obtained as a generalized derivative of the Heaviside function，and its higher derivative is also shown. Moreover，the convo- lutions，scales，compound transformations，orthogonality and Comb Dirac functions are recalled，respectively. Fi- nally，the relationship between Dirac δ-function and generalized Fourier transform is introduced，and we present an application to solve the Dirichlet boundary value problem of the Poisson equation. Related Articles | Metrics | Comments（0）

Select

Systematic error analysis of period of simple pendulum SHAO Yun College Physics    2022, 41 (1): 32-.   DOI: 10.16854 / j.cnki.1000-0712.210247 Abstract （3472）      PDF（pc） （353KB）（737）       Knowledge map    Save This paper analyzes and calculates the influence of the pendulum angle，the rotation of the ball，the mass of the suspension line，the air buoyancy and the air resistance on the period of the pendulum one by one. Tak- ing a 1 m length and 5° swing angle small amplitude pendulum as an example，the relative errors of the five factors are +0.45‰，+0.02‰，-0.45‰，+0.07‰，-0.14‰，respectively，and the total is only -0.05‰，which means that the five error factors almost cancel each other，and the systematic error of the small pendulum experiment is very small in theory. This paper gives a more detailed reasoning，calculation and analysis process，especially the reasoning process of air resistance moment，as well as charts and tables，for providing a more complete and accu- rate understanding. Finally，some necessary explanations are given in view of some possible deficiencies in people's understanding of air resistance. Related Articles | Metrics | Comments（0）

Select

Diffraction and splitting function of phase grating ZOU Yi-yun, LIN Jia-li, LU Yue-yuan, YAN Xiao-na College Physics    2021, 40 (11): 64-.   DOI: 10.16854 / j.cnki.1000-0712.210104 Abstract （2983）      PDF（pc） （407KB）（1023）       Knowledge map    Save Using the coherent superposition，diffractions are deduced when a plane wave incidents on a phase grating. Results show that the ±1 order diffraction of the phase grating can get the maximum intensity and realize the splitting function，overcoming the problems in amplitude grating where the 0 order diffraction has the maximum in- tensity but with no splitting function. The diffraction efficiency of ±1 order diffraction with respect to the duty ratio and phase introduced by the phase material are discussed. The method we provided here has implicit physical mean- ings and is easy to adapt to other diffraction structure. Related Articles | Metrics | Comments（0）

Select

Influence of spectrometer adjustment on the measurement of apex angle and minimum 　　deviation angle of a triangular prism LI Xin-jing, SONG Xin-bing College Physics    2021, 40 (8): 72-.   DOI: 10.16854 / j.cnki.1000-0712.200448 Abstract （2912）      PDF（pc） （459KB）（650）       Knowledge map    Save In the experiment of measuring the refractive index of a prism with a spectrophotometer，a key step is to adjust the object stage so that its main axis is perpendicular to the optical axes of the telescope and the collima- tor，which is called the standard case. It is analyzed that the influence on the measurement of apex angle and mini- mum deviation angle theoretically and experimentally when there is a deviation of the object stage. The experiments are performed for two cases. One case is that，in the telescope，it can be found that a green cross image reflectes from at least one surface of the double face plane mirror. In this case，the deviation is marked by recording the posi- tion of the green cross image. The other case is that the deviation of the object stage is measured with an extra sys- tem. In this case，the deviation degree of the object stage can be recorded directly. In experiment，the variation of the apex angle and minimum deviation angle of the prism with the deviation of the object stage is measured in the two cases. And the object stage’s deviation range，at which the experimental results has smaller deviations than standard measurement errors，is determined. Related Articles | Metrics | Comments（0）

Select

Home experiment: fractal geometry of crumpled paper ball LUO Jie, QIAN Jun College Physics    2021, 40 (10): 73-.   DOI: 10.16854 / j.cnki.1000-0712.200522 Abstract （2371）      PDF（pc） （267KB）（1037）       Knowledge map    Save During the pandemic period，experiments in home are set up in basic physics experiment course. Because of the simple preparation and easy measurement，the hand-crumpled paper ball experiment is chosen by many students. In this paper the fractal in the experiment of crumpled paper balls is discussed. The definition of fractal dimension is introduced to describe the internal irregularity of the crumpled paper balls. The fractal dimen- sion of normal A4 printing paper is measured experimentally and the influence of different paper hardness and paper layers on the fractal dimension of paper ball is studied. Related Articles | Metrics | Comments（0）

Select

Design experiment of university physics: research on demonstration device of Lissajous graphic WU Han¹, YU Yao¹, YOU Yin-tao¹, TANG Yong-jun¹, ZHANG Jin-long² College Physics    2021, 40 (10): 36-.   DOI: 10.16854 / j.cnki.1000-0712.210147 Abstract （2366）      PDF（pc） （276KB）（606）       Knowledge map    Save In this paper，a comprehensive design experiment of university physics，the self-making Lissajous graphic demonstration device is introduced. The reason why Lissajous figures is formed through theoretically analy- zing the thin film ' s forced vibration. The experimental results show that the shape and size of Lissajous figures change periodically when the frequency of the sound source increases. Finally，the effective surface tension value is estimated to be about 46.00 N / m through the measured resonance frequency when the surface area of latex ballon is twice the normal area，indicating that the device has certain practical applicability. Related Articles | Metrics | Comments（0）

Select

vibration law of Wilberforce pendulum JIANG Fu-jin¹, HAN Can² College Physics    2021, 40 (11): 15-.   DOI: 10.16854 / j.cnki.1000-0712.210083 Abstract （2333）      PDF（pc） （685KB）（1423）       Knowledge map    Save In this paper，a possible vibration model is conjectured according to the vibration characteristics of Wilberforce pendulum. Based on this model，the dynamic differential equations of Wilberforce pendulum are written out. Then the normal frequency and the analytical solution of the vibration are obtained. Finally，the numerical sim- ulation of the analytical solution is carried out and compared with the experimental data，which proves the rationali- ty of the conjecture Related Articles | Metrics | Comments（0）

Select

Gaussian and Gaussian-like integrals in physics WANG Meng, TAO Jun-qi, CHENG Jian-jian, ZHENG Hua College Physics    2021, 40 (5): 13-.   DOI: 10.16854 / j.cnki.1000-0712.200268 Abstract （2324）      PDF（pc） （317KB）（831）       Knowledge map    Save In this paper，we show how to calculate the different type Gaussian and Gaussian-like integrals with college-level mathematics. We also discuss the applications of the Gaussian and Gaussian-like integrals in Thermo- dynamics and Statistical Physics，Quantum Mechanics，Optics and Quantum Optics. Related Articles | Metrics | Comments（0）

Select

A simpler explanation of Thomas precession YANG Yi, LI Xiu-ling, LUO Cheng-lin College Physics    2021, 40 (5): 71-.   DOI: 10.16854 / j.cnki.1000-0712.200466 Abstract （2313）      PDF（pc） （372KB）（535）       Knowledge map    Save The discovery of Thomas precession is of great significance to the establishment of the concept of e- lectron spin. However，its physical images and conclusions are usually derived from the differential process of con- tinuous Lorentz transformation. The method is complicated and difficult to understand. In this article，based on the concept of shortening the length in the direction of motion in the special theory of relativity，it is surprising to find that Thomas precession angular velocity can be easily calculated by the integral effect of the angle difference be- tween the nuclear reference system and the electron reference system when the electron moves around the nuclear for a full circle. Related Articles | Metrics | Comments（0）

Select

Electrodynamic explanation of faraday magneto-optical rotation effect XIAO Tian-ning, WANG Shuan-hu College Physics    2021, 40 (9): 72-.   DOI: 10.16854 / j.cnki.1000- 0712.210068 Abstract （2268）      PDF（pc） （463KB）（670）       Knowledge map    Save Faraday magneto-optical rotation effect is a phenomenon that applying an external magnetic field to an isotropic medium will induce the optical rotation property. In this paper， light is regarded as an electromagnetic wave. By using the method of electrodynamics， starting from the equation of motion of electrons in an isotropic me- dium under an external magnetic field， the change of the system caused by the magnetic field will be analyzed. And then the relative dielectric tensor is obtained， which is solved by combining with Maxwell equations. By using the simple knowledge of electrodynamics， we can strictly deduce that the eigenstates of magneto-optical system must be right-handed and left-handed polarization. Furthermore， we can make readers better understand the source of fara- day effect in the perspective of eigenvalue problem. Related Articles | Metrics | Comments（0）

Select

Design and practice of ideological education in college physics ———taking particle mechanics as an example LONG Xiao-yan¹, XIE Hai-yan², WU Shi¹, ZHANG Yi-xun¹, LI Jia-ding¹ College Physics    2022, 41 (1): 50-.   DOI: 10.16854 / j.cnki.1000-0712.210166 Abstract （2203）      PDF（pc） （563KB）（663）       Knowledge map    Save It is of great significance and imperative to strengthen political and ideological education in teaching. In order to deepen the teaching reform of college physics，the teaching design of ideological education is carried out under the blended learning mode by using the effective teaching method based on the traditional teaching and aiming at knowledge goal. Through the design and practice of on-line，off-line and examination，combining the lec- ture of ideological education by famous teachers，the course mode of ideological education is formed. The applica- tion of this model takes the first chapter，particle mechanics，as an example. The practice shows that the education quality is improved. Related Articles | Metrics | Comments（0）

Select

Calculation of states density in solid state physics DU Lin, TIAN Hong-yu, REN Chong-dan College Physics    2022, 41 (4): 77-.   DOI: 10.16854 /j.cnki.1000-0712.210438 Abstract （2155）      PDF（pc） （887KB）（849）       Knowledge map    Save The electronic density of states is the number of states in the unit energy range.It is a physical quantity closely related to electronic energy band structure.In order to calculate the specific heat of electrons and the transport properties of crystals,a more accurate method must be used to calculate the electronic density of states.The processing of this in general textbooks usually adopts simplified models,which does not reflect the calculation ideas of states density in general.In this article,two-dimensional graphene and three-dimensional face-centered cubic lattice are explained in detail based on the formula of electronic density of states.The calculation steps of the density and a detailed explanation based on numerical calculation are given. Related Articles | Metrics | Comments（0）

Select

Application of tensor analysis in deriving geometric equations and equilibrium differential equations of elasticity in cylindrical coordinates and spherical coordinates ZHOU Zheng-feng College Physics    2022, 41 (11): 4-.   DOI: 10.16854 /j.cnki.1000-0712.220043 Abstract （2144）      PDF（pc） （226KB）（949）       Knowledge map    Save First, using the relations of the unit vectors between orthogonal curvilinear coordinates and Cartesian coordinates, and the invariability of the unit vectors in Cartesian coordinates, the gradient operator in both coordinates, and the partial derivative of the unit vectors to the coordinates are derived from the perspective of the transformation of the unit vectors. Then, using the fundamentals of the theorems of tensor field, the gradient of displacement vector and the divergence of stress tensor are derived by derivation. Last, the geometric equations of strain and the differential equations of equilibrium are derived in details in cylindrical coordinates and spherical coordinates from their forms expressed by tensor. Related Articles | Metrics | Comments（0）

Select

Green functions and their applications to ordinary differential equations QIAN Guang-yao, YAN Ruo-kun, WANG Ze-xi, ZHENG Shen-zhou College Physics    2021, 40 (9): 81-.   DOI: 10.16854 / j.cnki.1000- 0712.210142 Abstract （2120）      PDF（pc） （460KB）（628）       Knowledge map    Save In this paper， we are devoted to a review of the Green functions and the Green 　　function method for solving the initial and boundary value problems of various ordinary 　　differential equations. For the initial value prob- lem of linear ordinary differential equation 　　of first order， the formula of Green function and the solution represented 　　by Green function are given. For the boundary value problem and initial value problem of linear 　　ordinary differential equation of second order， the calculation of Green function and the 　　solution represented by Green function are shown， respectively. The calculation of Green 　　function and the solution representation by Green function for Sturm- 　　Liouville problem satisfying general initial value conditions are established. For the 　　un-mixed and mixed boundary value problems of linear ordinary differential equations of second 　　order， we also consider how to find Green function and the solution represented by Green 　　function， respectively. Finally， For the boundary value problem of higher or- der linear ordinary 　　differential equations， the Green function and the solution expressed by Green function 　　are ob- 　　tained. Related Articles | Metrics | Comments（0）

Select

A deduction method of mass-velocity relationship in special theory of relativity FENG Shi-meng College Physics    2021, 40 (6): 32-.   DOI: 10.16854 / j.cnki.1000-0712.200506 Abstract （2003）      PDF（pc） （616KB）（504）       Knowledge map    Save The mass-velocity relationship is an important conclusion of the theory of relativity. Most textbooks use two objects to collide completely in-elastically for observing the speed change from different frames of refer- ence，and obtain the mass-speed relationship. This paper uses the Lorentz transformation of space-time in the spe- cial theory of relativity to prove the invariance of the force in the direction of motion in the two inertial reference frames. Then，Newton's second law is directly to derive the relationship between mass and speed. This derivation method is relatively simple. which is very conducive to the understanding of junior college students. Related Articles | Metrics | Comments（0）

Select

Exploration and integration of ideological and political elements in college physics teaching ZHU Xian-zhong, CHEN Fei-ming, FENG Cun-fang College Physics    2021, 40 (6): 66-.   DOI: 10.16854 /j.cnki.1000-0712.200423 Abstract （1950）      PDF（pc） （805KB）（619）       Knowledge map    Save How to excavate ideological and political education ( IPE) resources which richly containe in college physics and to exert them on students in an imperceptible way，is an urgent problem for physics teachers to solve. According to the content of college physics course，the content system of IPE with its structural relationship is combed in this paper，which embodes the political and epochal features. Two searching methods of IPE materials are provided，and the educational function of the same important IPE materials in the knowledge system of physics is analyzed in order to provide basic ideas for constructing IPE material resources. Some methods of integrating the elements of IPE in the process of teaching implementation are discussed so as to provide support for the implementation of recessive teaching strategy. Related Articles | Metrics | Comments（0）

Select

The four quantum numbers of electrons in an atom HUANG Yong-yi College Physics    2021, 40 (5): 8-.   DOI: 10.16854 / j.cnki.1000-0712.200272 Abstract （1930）      PDF（pc） （397KB）（444）       Knowledge map    Save The paper expounds the origins of the four quantum numbers of electrons in an atom and briefly presents the applications of the four quantum numbers: the electron shells of an atom and the Pauli exclusion prin- ciple. Related Articles | Metrics | Comments（0）

Select

Spherically averaging function and deduction of its differential equation CAI Jun, LI Min, WANG Qun College Physics    2021, 40 (8): 16-.   DOI: 10.16854 / j.cnki.1000-0712.210016 Abstract （1927）      PDF（pc） （187KB）（492）       Knowledge map    Save The initial- value problem of the wave equation in the three-dimensional case is a very important content in the course of methods of mathematical physics. In this paper，we discuss the definition of the spherically averaging function and how to build up the partial differential equation satisfied when we use the method of spherical means to solve this problem. A more concise procedure to deduce the equation of spherically averaging function is provided based on the analysis of the deduction appeared in the textbooks. Our discussion will clarify the basic meaning of the spherically averaged function and is benefit to the teaching and studying of the method of spherical means and other solutions to the equations of mathematical physics in three-dimensional spherical coordinates. Related Articles | Metrics | Comments（0）