共查询到20条相似文献,搜索用时 93 毫秒
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转换,即更改、改换,它是当事物的发展遇到某种障碍时,将困难的、复杂的情况转换成容易的、简单的情况的一种思想方法.这种思想方法在物理实验中是经常用到的. 相似文献
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做实验的主人--写给学习物理实验的学生 总被引:3,自引:1,他引:2
在学习实验时应注意学习探索,本文从实验课上学什么,如何在探索中学习,如何进行误差分析,实验结果如何评价,怎样认识验证性实验,怎样理解实验的物理思想,怎样在实验过程中提出问题等几方面讨论了学生怎样做实验的主人. 相似文献
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物理实验中的思想方法与学生的科学素质 总被引:2,自引:1,他引:1
用具体实例重点分析了物理实验中的控制变量法、转换法、替代法、模拟法对学生科学素质的影响,充分展示了在物理实验中对学生进行思想方法教育的重要性和现实性。 相似文献
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在高中物理实验教学过程中,我们不仅要让学生动手实验,探索物理规律,同时还要渗透物理实验思想与物理实验方法以及实验误差分析的教育.在设计实验方案、安排实验、进行实验测量时,都要采取适当的方法或措施来减小测量中的误差.本文就谈谈在物理实验中所涉及的误差问题以及减小测量误差的几种常用方法. 相似文献
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J. Cugnon 《Nuclear Physics A》1973,208(2):333-359
The imaginary part of the optical-model potential for the scattering of nucleons by nuclei is studied in the frame of the shell-model approach to nuclear reactions. Special attention is paid to the one-hole target nuclei. The imaginary part of the optical-model potential in the second order in the nucleon-nucleus interaction is divided into two parts. The first corresponds to the average resonant scattering. The second corresponds to the inelastic scattering leading to the non-collective states of the target nuclei. A local potential equivalent to the non-local theoretical one is constructed in order to facilitate comparison with experiment. Numerical calculations concern the scattering of 14.5 MeV protons by 39K. It is found that the imaginary part depends upon the angular momentum and that its radial variation is governed by strong shell effects. The predicted absorption is approximately 60% of the experimental one. The average resonant scattering contributes to the imaginary part of the optical-model potential as much as the inelastic non-collective excitations of the target. 相似文献
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Keefe CD 《Journal of Molecular Spectroscopy》2001,205(2):261-268
The Kramers-Kronig transformation has been extensively applied in optical spectroscopy to calculate the real component of an optical quantity from the imaginary component, such as the real refractive index from the imaginary component, or vice versa. In this paper, the traditional proof of the Kramers-Kronig transformation, and its application to the complex refractive index, complex dielectric constant, and complex molar polarizability, are reviewed. Often the imaginary components of these quantities are fitted with standard lineshapes such as the Gaussian, Lorentzian, or Classical Damped Harmonic Oscillator (CDHO) lineshapes. It is shown that the usual Gaussian and Lorentzian lineshapes do not meet the physical criteria of these imaginary components nor the conditions of the Kramers-Kronig transformation since they are not odd functions of wavenumber. However, the CDHO lineshape meets the physical criteria of the imaginary components of these optical quantities and the Kramers-Kronig transformation. Modifications are presented that make the Gaussian and Lorentzian odd. The Gaussian decays so fast that the modification is not needed in practice; however, the Lorentzian is much slower to decay and thus modification is necessary whenever fitting peaks below approximately 250 cm(-1). Since the computational difference between the usual Lorentzian and modified Lorentzian is negligible, the author recommends that only the modified Lorentzian be used when fitting bands with a Lorentzian lineshape. Copyright 2001 Academic Press. 相似文献
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利用基尔霍夫衍射理论计算模拟了四圆孔径衍射屏在菲涅耳深区形成的衍射光场的强度、零值线和相位的分布,发现衍射光场亮斑关于中心呈对称分布,在距离衍射屏较近的观察面上,光强值为零的点组成光强零值线段,该线段上光强等值线的离心率都接近或等于1,其两侧的光强值变化非常剧烈。复振幅的实部和虚部零值线多为封闭的曲线,零值线交叉点的个数为偶数,并且正负相位奇异点的个数相等。特殊相位奇异点周围的相位不仅呈对称分布,而且该点的拓扑荷的值近似为零。随着光波的传播,在不同的观察面上光强零值线段逐渐变短,最终趋于一点。 相似文献
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The results of studies of the scalar and vector energy characteristics of a real acoustic interference field in a shallow sea are presented based on notions of monochromatic fields and common field vector ratios. The importance of the quantities under consideration is that they are the components of the energy-pulse tensor of the acoustic field. The horizontal components of the complex intensity vector are represented only by its real parts, i.e., the imaginary parts of the horizontal components of the intensity vector are equal to zero; the vertical component has both real and imaginary parts. The imaginary part of the vertical component of the complex intensity vector is related to the interference field of acoustic pressure (the potential energy). The energy characteristics of the acoustic field in a shallow sea obtained during a real experiment correspond to the common theoretical field ratios. 相似文献
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H. Ngô 《Nuclear Physics A》1982,390(2):198-206
Neutron and proton-40Ca elastic scattering angular distributions and total reaction cross sections are calculated between 10 and 40 MeV using the microscopic optical potential derived by Bouyssy et al. within the nuclear structure approach. Direct comparison with experiment confirms that our calculation reproduces the imaginary potential at low energy for protons, but it gives insufficient absorption above the deuteron pick-up threshold. A renormalization of both the real and the imaginary parts of the potential leads to good agreement with the data. For both parts of the potential this renormalization is compatible with the renormalization factors obtained by Bouyssy et al. from a comparison of calculated and phenomenological volume integrals. 相似文献
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An antisymmetrized microscopic calculation of the optical potential for nucleon-40Ca elastic scattering is derived. RPA correlations taken into account in the one-particle mass operator are shown to bring a correction to the first-order real potential at low energies and to lead to an imaginary potential. Both are calculated for incident nucleon energies between 10 and 50 MeV. Their general properties are studied in great detail and, after comparison with empirical imaginary potentials, the reliability of such an approach is discussed according to the value of the incident energy. 相似文献
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An inhomogeneously broadened two-mode laser system with cross-correlations between the real and imag- inary parts of quantum noise is considered. The Fokker-Planek equation of the system is derived by the phase-locking method. The steady-state probability distribution, the mean light intensity, the normalization autocorrelation function, and cross correlation function are calculated. The results indicate that: (i) The cross-correlation between the real and imaginary parts of quantum noise can cause the stationary probability distribution from one peak structure to two extrema structure when the laser system is operated above threshold; (ii) The cross-correlation between the real and imaginary parts of quantum noise enhance the light intensity fluctuation and decrease the laser output when the laser system is operated below or near threshold; (iii) The effect of the cross-correlation between the real and imaginary parts of quantum noise is very weak on the stationary properties when the laser system is operated far above threshold. 相似文献
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当同时使用离子(或电子)回旋及中性束注入方式加热等离子体时,高能量粒子的能量分布函数一般应为尾部隆起(简称尾隆)分布。这种具有正能量梯度区域的分布函数更容易激发不稳定性,同时由于分布函数尾部隆起,在色散关系中引入了新的色散函数。主要研究了这种新色散函数的计算方法,结果表明:色散函数实部是关于原点对称的奇函数;而虚部则是关于纵轴对称的偶函数。色散函数的实部有2~4个极值点且极值点的位置与尾隆分布函数的能量梯度⊿有关、虚部有1~3个极值点但极值点位置与⊿无关。当其宗量趋于无穷大时,色散函数的值趋于零。当尾隆分布趋近于麦克斯韦分布时,用该方法计算的结果与色散函数表中给出的结果非常吻合。 相似文献
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当同时使用离子(或电子)回旋及中性束注入方式加热等离子体时,高能量粒子的能量分布函数一般应为尾部隆起(简称尾隆)分布。这种具有正能量梯度区域的分布函数更容易激发不稳定性,同时由于分布函数尾部隆起,在色散关系中引入了新的色散函数。主要研究了这种新色散函数的计算方法,结果表明:色散函数实部是关于原点对称的奇函数;而虚部则是关于纵轴对称的偶函数。色散函数的实部有2~4 个极值点且极值点的位置与尾隆分布函数的能量梯度Δ 有关、虚部有1~3 个极值点但极值点位置与Δ 无关。当其宗量趋于无穷大时,色散函数的值趋于零。当尾隆分布趋近于麦克斯韦分布时,用该方法计算的结果与色散函数表中给出的结果非常吻合。 相似文献