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AS Module 1 Particles and Quantum Phenomena

Introduction  The two themes explored in this module are those of particles and of electromagnetic radiation and quantum phenomena. The concept of anti-particles is introduced as are quarks and anti-quarks. The particle and the wave models are brought together. Most of this module consists of material from the AS criteria for Physics and develops material studied in the Key Stage 4 science courses. N.B. All the formula in this module (below) will be given on the data sheet.

10.1 Particles

The Particle Adventure: 

10.1.1 Constituents of the atom  

atomic structure

Proton, neutron, electron 

Charges, relative masses.  


Atomic mass unit is not required  

10.1.2 Evidence for existence of the nucleus


Qualitative study of  Rutherford scattering  

Proton number Z, nucleon number A, isotopes


10.1.3 Particles, antiparticles and photons:


particle adventure: antiparticles


the four interactions


S-Cool: antimatter, particle accelerators, pair production and annihilation 




S-Cool: interactions and Feynman diagrams

Electron, positron 

Proton, antiproton 

Neutrino, antineutrino


Photon model of electromagnetic radiation


the Planck constant,


E = hf


Weak interaction, limited to changes in which a proton changes to a neutron or vice versa


Pair production; annihilation of a particle and its antiparticle releases energy; 

the use of E = mc2 is not required


Concept of exchange particles to explain forces between elementary particles    


Beta decay Simple Feynman diagrams to show how a reaction occurs in terms of particles going in and out and exchange particles: limited to B- decay, B+ decay, electron capture, neutrino – neutron collisions, antineutrino – proton collisions and electron – proton collisions
10.1.4 Classification of particles

Hadrons and Leptons


S-Cool: Hadrons and Leptons



baryons (proton, neutron) 


mesons (pion, kaon)


Candidates should know that the proton is the only stable baryon into which other baryons eventually decay; in particular the decay of the neutron should be known








Candidates will not be required to remember, but will be expected to be familiar with, baryon numbers and lepton numbers for individual particles and antiparticles.  

10.1.5 Quarks and antiquarks


Particle adventure: quarks 

and more quarks

Up (u), down (d) and strange (s) quarks only. 


Properties of quarks: charge, baryon number and strangeness 


Combinations of quarks and antiquarks are required for baryons (proton and neutron only) and for mesons (pion and kaon only)


Change of quark character in B- decay and  B+ decay


Application of the conservation laws for charge, baryon number and strangeness to particle interactions

Past module questions on Particle Physics + Mark Scheme

Some web sites that seem relevant 

Summary questions on particle physics

S-Cool's site for info on Particle Physics

Delphi - particle detective work

10.2 Electromagnetic radiation and quantum phenomena  

10.2.1 Refraction at a plane surface


S-Cool: refraction

Refractive index, n; candidates are not expected to recall methods for determining refractive indices 

Snell’s law of refraction 


sinq1/ sinq2  =c1/c2

1n2 = n2 / n1

Total internal reflection including calculations of critical angle, 

sin qc = 1 / n

Simple treatment of fibre optics including function of cladding with lower refractive index around central core limited to step index only;

candidates should be familiar with modern applications of fibre optics, e.g. endoscopy, communications, etc.  

10.2.2 The photoelectric effect. 

Photoelectric effect - another link

S-Cool: photoelectric effect

Treatment limited to energy considerations only; the stopping potential experiment is not required; 

work function f

photoelectric equation:

hf f E

10.2.3 Collisions of electrons with atoms 

how does a fluorescent lamp work?

S-Cool: electron energy levels

Ionisation, excitation 

The electronvolt 

Understanding of the role of ionisation and excitation in the fluorescent tube; 

line spectra (e.g. of atomic hydrogen) as evidence of transitions between discrete energy levels Energy levels, photon emission  

hf = E1 - E2

10.2.4 Wave-particle duality

S-Cool: wave particle duality

Candidates should know that electron diffraction suggests the wave nature of particles and the photoelectric effect suggests the particle nature of electromagnetic waves;


details of particular methods of showing particle diffraction are not expected 


de Broglie wavelength 

l  =   h   /  mv

Past module questions on  Electromagnetic radiation and Quantum Effects plus mark schemes



Conservation laws for charge, baryon number and strangeness

Conservation of lepton baryon number homework answers

Refraction homework

Answers: email me for them 

Photoelectric effect and wave particle duality

Model answers for these questions

Electron energy levels questions

Electron energy levels answers

Revision Resources 

Module 1 - Interactive Glossary

S-Cool's site for info on Quantum Physics

Online exam paper with mark scheme

Please email me any other links you find useful :-)