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A-level物理|量子物理与核子物理考前总结,提分必备!

  随着A2物理的逐渐深化,有两个对于学生们相对陌生章节慢慢的的困扰了越来越多的学生。那就是量子物理与核子物理(quantum physics and nuclear physics)。不光因为他对于学生们模糊的定义,让大家难以理解这到底是什么,更是由于很多陌生繁琐的定理与公式不断地涌现,不知如何才能熟练掌握。那么接下来,我将从几个部分细细讲解一下这两章节,最终目的是看过这篇文章的同学们能够在paper4中遇到此章节的题,有清晰的思路并且将分数稳稳拿住。

  一.the definition of key vocabularies.

  -Particle model: objects that are hard, have mass and move about according to laws of Newtonian mechanics

  -Wave model: shaped like a sine graph, do not have mass or charge. Their defining characteristics are diffraction and interference

  -Photoelectric effect: when an electromagnetic radiation of sufficiently high frequency falls on a metal surface, electrons are emitted and the emitted electrons are called photoelectrons

  -Photoelectric current: current due to photoelectrons

  -Photon: each quantum (particle) of electromagnetic radiation

  -Work function: minimum amount of energy required by an electron to escape its surface

  -Matter wave: a moving particle of matter of momentum will have an associated wave of wavelength where

  -Under normal conditions, an atom is in its ground state where it posses the minimum possible energy

  -Transition: shifting of electrons between energy levels

  -Mass defect : the difference between the total mass of the individual, separate nucleons and the mass of the nucleus

  -Binding energy : the minimum external energy required to separate all the neutrons and protons of a nucleus. It is also the energy released when the nucleus is assembled from its constituent nucleons

  -Binding energy per nucleon of a nucleus is the ratio of the total binding energy to its nucleon number

  -Fission: process in which a massive nucleus splits to form two smaller fragments-Fusion: process by which two very light nuclei join together to form a heavier nucleus

  -Random: impossible to predict and each nucleus has the same probability of decaying per unit time

  -Spontaneous: not affected by external factors such as the presence of other nuclei, temperature and pressure

  -The activity of a radioactive sample is the rate at which nuclei decay or disintegrate

  -The decay constant is the probability that an individual nucleus will decay per unit time interval

  -The half life of a radioactive is the mean time taken for half of the active nuclei in a sample to decay

  二. Key rules

  Laws of Photoelectric Emission:

  • 1st Law: number of photoelectrons emitted per second is directly proportional to intensity of incident radiation

  • 2nd Law: max kinetic energy of photoelectrons is directly proportional to the frequency of the incident radiation but independent of its intensity

  • 3rd Law: for every metal, there is a minimum frequency of incident radiation below which photoelectric emission does not take place; threshold frequency

  • Threshold frequency: minimum frequency required to release electrons from the surface of a metal

  三. important formula needed to do calculation

  Einstein’s Photoelectric Equation:

  The frequency of the emitted radiation:

  Einstein’s mass-energy relation:

  四.example questions

  下面我们来分别简单看两道题,同学们在确保已经掌握了以上知识要点之后,可以自己给自己做个小测试。

  题目的难度虽然不大,但是要思路来的快,必须要对基础的公式,词汇以及定理有着深刻的印象,加之娴熟的运用。当然了,仅仅做这两道题是远远不够的,要想在A2考试中占得优势,还得在勤加努力才行。

  关于量子物理与核子物理的内容就讲到这里,想要了解更多A-level物理课程的信息,可以咨询52Alevel老师。


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