A-level物理| 量子物理与核子物理总结，提分必备！

A-level物理| 量子物理与核子物理总结，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 emittedand the emitted electrons are calledphotoelectrons

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 momentumwill have an associated wave of wavelengthwhere

Under normal conditions, an atom is in itsground statewhere 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 nucleonof 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

Theactivityof a radioactive sample is the rate at which nuclei decay or disintegrate

Thedecay constantis the probability that an individual nucleus will decay per unit time interval

Thehalf lifeof a radioactive is the mean time taken for half of the active nuclei in a sampleto decay

二. Key rulesLaws of Photoelectric Emission:?1stLaw:number of photoelectrons emitted per second is directly proportional to intensity of incident radiation?2ndLaw:max kinetic energy of photoelectrons is directly proportional to the frequency of the incident radiation but independent of its intensity?3rdLaw: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。