AQA A Level Physics复习笔记8.3.2 Decay Equations
Changes in N and Z by Radioactive Decay There are four reasons why a nucleus might become unstable, and these determine which decay mode will occur Too many neutrons Decays through beta-minu...
IB DP Maths: AA HL复习笔记4.6.3 Standardisation of Normal Variables
Standard Normal Distribution What is the standard normal distribution? The standard normal distribution is a normal distribution where the mean is 0 and the standard deviation is 1Why is the standa...
不参与U.S.News排名，但实力强劲的美国大学有哪些？
在美国有相当一部分院校是不参与U.S.News排名的，原因各不相同，而作为申请者，如果在选校时忽略了这些“无名”但实力强劲的学校，很有可能会与自己真正的梦校擦肩而过。今天小编来聊聊那些长期被忽视，但学术实力...
AQA A Level Physics复习笔记8.3.1 Nuclear Instability
Nuclear Stability Graph The most common elements in the universe all tend to have values of N and Z less than 20 (plus iron which has Z = 26, N = 30) Where: N = number of neutrons Z = number...
AQA A Level Physics复习笔记8.2.4 Applications of Radioactivity
Radioactive Dating The isotope carbon-14 is commonly used in radioactive dating It forms as a result of cosmic rays knocking out neutrons from nuclei, which then collide with nitrogen nuclei...
AQA A Level Physics复习笔记8.2.3 Half-Life
Half-Life Half-life is defined as: The time taken for the initial number of nuclei to halve for a particular isotope This means when a time equal to the half-life has passed, the activity of...
AQA A Level Physics复习笔记8.2.2 Exponential Decay
Exponential Decay In radioactive decay, the number of undecayed nuclei falls very rapidly, without ever reaching zero Such a model is known as exponential decay The graph of number of...
QS世界大学排名中，中国在前20强中有哪些专业？
2022QS世界大学学科排名里，中国大陆共有93所高校上榜，数量排名全球第三，仅次于英国（105所）和美国（227所），其中10所高校为首次上榜。多年来，中国大陆上榜院校数量稳步上升：2018年上榜高校数量为74所。 在...
Edexcel IGCSE Chemistry 复习笔记 1.9.1 Explaining Conductivity
Edexcel IGCSE Chemistry 复习笔记 1.9.1 Explaining Conductivity Conductivity of Covalent Compounds Electric current is the flow of charged particles This usually refers to electrons, but it c...
AQA A Level Physics复习笔记8.2.1 Radioactive Decay
Radioactive Decay Radioactive decay is defined as: The spontaneous disintegration of a nucleus to form a more stable nucleus, resulting in the emission of an alpha, beta or gamma particle Ra...
Edexcel IGCSE Chemistry 复习笔记 1.8.1 Metallic Bonding
Edexcel IGCSE Chemistry 复习笔记 1.8.1 Metallic Bonding Metallic Bonding Metal atoms are held together strongly by metallic bonding Within the metal lattice, the atoms lose their valence ele...
AQA A Level Physics复习笔记8.1.7 Required Practical: Inverse Square-Law for Gamma Radiation
Required Practical: Inverse Square-Law for Gamma Radiation Aim of the Experiment The aim of this experiment is to verify the inverse square law for gamma radiation of a known gamma-emitting ...
