2020-05-25 2134浏览
ALevel考试科目众多,ALevel物理就是其中最热门的科目之一,很多考生在选课的时候都会选择物理考试,在物理备考之中,量子和核子是非常核心的考点,下面小编就为大家分析这两大考点,希望能够帮助到大家!
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。
以上就是ALevel物理中量子和核子知识点,希望大家能够好好复习,提高备考能力,另外语法的学习大家也不能放松,这样才能顺利通过考试,如果还想了解alevel考试介绍、alevel国际课程的信息,可以在线咨询我们或添加客服微信kewo11!
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