Which equations recur most across this content?

The decay law $N = N_0 e^{-\lambda t}$ with activity $A = \lambda N$ and half-life $T_{1/2} = \frac{\ln 2}{\lambda}$, mass-energy equivalence $E = mc^2$ and binding energy $E = \Delta m c^2$, the quark-charge sums for protons and neutrons, and (for the medical physics option) X-ray attenuation $I = I_0 e^{-\mu x}$ and acoustic impedance $Z = \rho c$.

What is the most common mistake in this content?

Saying gamma is the most ionising radiation: it is the least ionising but the most penetrating, the reverse of alpha. Close behind are leaving the half-life in hours or days when finding the decay constant for an activity in becquerel, forgetting the antineutrino in beta-minus decay, using the mass defect in grams rather than kilograms in $E = \Delta m c^2$, and confusing fission (splitting heavy nuclei) with fusion (joining light ones).

How is half-life examined in Eduqas Physics?

Typically you find the decay constant from the half-life with $\lambda = \frac{\ln 2}{T_{1/2}}$, then use $N = N_0 e^{-\lambda t}$ or $A = A_0 e^{-\lambda t}$ to find the number of nuclei or the activity at a later time, or work the other way from a measured count rate. Graph questions may use a log-linear plot to find the decay constant from the gradient.

How should I revise nuclear and particle physics?

Learn the quark compositions and conservation laws and practise checking reactions, drill the radioactive decay calculations and half-life, and learn the binding-energy-per-nucleon curve and the fission-fusion argument. Crucially, find out which Component 3 option your school teaches and revise only that one in depth (medical physics is the most common).

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Eduqas A-Level Physics Nuclear and particle physics: quarks, radioactivity, binding energy and the options

Q: What does Eduqas nuclear and particle physics cover?

It covers particles and nuclear structure with the nuclear model, hadrons and leptons, the quark composition of protons and neutrons and conservation laws, nuclear decay with alpha, beta and gamma radiation, activity, the exponential decay law and half-life, nuclear energy with mass-energy equivalence, binding energy, fission and fusion, and the four Component 3 options (alternating currents, medical physics, the physics of sports, energy and the environment), of which one is studied.

A deep-dive Eduqas A-Level Physics guide to the nuclear, particle and options content within Component 3. Covers particles and nuclear structure with quarks and leptons, nuclear decay and half-life, nuclear energy with binding energy, fission and fusion, and the four options with medical physics in detail, with the calculations Eduqas repeats.

Generated by Claude Opus 4.816 min readA720QS Component 3Updated 2026-06-02

Reviewed by: AI editorial process; not yet individually human-reviewed

Jump to a section

What this module actually demands
Particles, decay and nuclear energy
The options
How this module is examined
Check your knowledge

What this module actually demands

The nuclear, particle and options content completes Component 3 (Light, Nuclei and Options). It builds the modern picture of matter from quarks and leptons, develops radioactivity and the mathematics of decay, explains nuclear energy through binding energy and the fission-fusion argument, and ends with one applied option. The examiners reward fluent decay calculations, precise conservation-law reasoning, and clear understanding of the binding-energy curve.

This guide walks through the topics in order and sets out the exam patterns Eduqas repeats. Each topic has a matching dot-point page with practice; this overview ties them together.

Particles, decay and nuclear energy

Particles and nuclear structure describes the nuclear model, classifies particles into hadrons (baryons and mesons) and leptons, gives the quark composition of protons and neutrons, and applies the conservation laws of charge, baryon number and lepton number. Nuclear decay describes alpha, beta and gamma radiation and their properties, the random and spontaneous nature of decay, activity and the decay constant, the exponential decay law, and half-life.

Nuclear energy uses mass-energy equivalence and the mass defect to define binding energy, interprets the binding energy per nucleon curve, and explains why both fission and fusion release energy.

The options

The physics of options gives an overview of the four Component 3 options: alternating currents, medical physics, the physics of sports, and energy and the environment, of which a school teaches one. Medical physics covers the most widely taught option in detail: the production and attenuation of X-rays, ultrasound imaging and acoustic impedance, PET scanning and positron annihilation, and radiation dose and its biological effect.

How this module is examined

A typical Eduqas profile for this content:

Calculations. Decay constant, activity and the number of nuclei from the decay law, half-life, quark-charge sums, energy released from a mass defect, and (for medical physics) X-ray attenuation.
Graph questions. Log-linear decay plots and the binding energy per nucleon curve.
Explanation and definition. Properties of alpha, beta and gamma radiation, conservation laws in reactions, the fission-fusion argument from the binding-energy curve, and (for medical physics) annihilation and imaging methods.
Equation writing. Balancing nuclear decay and reaction equations.

Check your knowledge

A mix of recall and calculation questions covering the module. Attempt them under timed conditions, then check against the solutions.

State the quark composition of a neutron. (1 mark)
State what beta-minus radiation is. (1 mark)
An isotope has a decay constant of $0.040\ \text{s}^{-1}$ . Find its half-life. (2 marks)
A reaction has a mass defect of $1.0 \times 10^{-28}\ \text{kg}$ . Find the energy released ( $c = 3.0 \times 10^{8}\ \text{m s}^{-1}$ ). (2 marks)
State why energy is released when light nuclei undergo fusion. (2 marks)
State the unit of absorbed radiation dose. (1 mark)

Sources & how we know this

Eduqas GCE AS/A Level Physics specification (A720QS) — WJEC Eduqas (2015)