## GCE A-Level物理课程大纲

## Chapter 20: Nuclear Physics

## 章节主题：

The nucleus

Isotopes

Nuclear processes

Mass defect and nuclear binding energy

Radioactive decay

Biological effects of radiation

## 题库：

## 学习目标：

(a) Infer from the results of the Rutherford α-particle scattering experiment the existence and small size of the atomic nucleus.

(b) Distinguish between nucleon number (mass number) and proton number (atomic number).

(c) Show an understanding that an element can exist in various isotopic forms each with a different number of neutrons in the nucleus.

(d) Use the usual notation for the representation of nuclides and represent simple nuclear reactions by nuclear equations.

(e) State and apply to problem solving the concept that nucleon number, charge and mass-energy are all conserved in nuclear processes.

(f) Show an understanding of the concept of mass defect.

(g) Recall and apply the equivalence between energy and mass as represented by E = mc² to solve problems.

(h) Show an understanding of the concept of nuclear binding energy and its relation to mass defect.

(i) Sketch the variation of binding energy per nucleon with nucleon number.

(j) Explain the relevance of binding energy per nucleon to nuclear fission and to nuclear fusion.

(k) Show an understanding of the spontaneous and random nature of nuclear decay.

(l) Infer the random nature of radioactive decay from the fluctuations in count rate.

(m) Show an understanding of the origin and significance of background radiation.

(n) Show an understanding of the nature of α, β and γ radiation.

(o) Show an understanding of how the conservation laws for energy and momentum in β decay were used to predict the existence of the neutrino (knowledge of antineutrino and antiparticles are not required).

(p) Define the terms activity and decay constant and recall and solve problems using the equation A = λN.

(q) Infer and sketch the exponential nature of radioactive decay and solve problems using the relationship x = x₀ exp (-λt) where x could represent activity, number of undecayed particles or received count rate.

(r) Define and use half-life as the time taken for a quantity x to reduce to half its initial value.

(s) Solve problems using the relation λ = ln2 / t₁/₂

(t) Discuss qualitatively the effects, both direct and indirect, of ionizing radiation on living tissues and cells