Modern Physics · Chapter

Nuclear Physics

Model radioactivity, decay, nuclear structure, and evidence-based reasoning about unseen processes.

Start chapter Next: Special Relativity

Learning Path

Checkpoint 1: Atomic nucleus

Models of the Atom

Compare Thomson, Rutherford, and nuclear models using scattering evidence and model limitations.

Checkpoint 2: Radioactive decay

Half-life and Random Decay

Use dice and decay simulations to connect random events, exponential trends, activity, and half-life.

Checkpoint 3: Radiation

Detect and Compare Radiation

Use Geiger and penetration models to compare alpha, beta, and gamma radiation.

Checkpoint 4: Nuclear evidence

Evidence from Scattering and X-rays

Use Bragg and related models to connect experimental patterns with structure and evidence.

Checkpoint 5: Nuclear systems

Model Nuclear Interactions

Explore larger nuclear-system models after the core evidence and decay ideas are clear.

Chapter Lens

How do models and radiation evidence help us reason about the atomic nucleus and radioactive decay?

Atomic models changed when evidence showed that atoms contain a small, dense, positively charged nucleus.
Radioactive decay is random for a single nucleus but predictable statistically for a large sample.
Alpha, beta, and gamma radiation differ in charge, mass, ionising power, and penetrating ability.

Misconception Watch

Radioactive decay is random for individual nuclei, but large samples follow predictable statistical patterns.
Half-life does not mean all radiation disappears after one half-life.
Penetrating power and ionising power are different properties.

Chapter Concept Checks

1. What did Rutherford's scattering experiment suggest about the atom?

Answer: Most mass and positive charge are concentrated in a small nucleus.

Distractors to watch for: Atoms are solid spheres with no internal structure. / Electrons are heavier than nuclei. / All alpha particles pass straight through every atom.

2. What does half-life describe?

Answer: The time taken for the number of undecayed nuclei or activity to fall to half its value.

Distractors to watch for: The time taken for every nucleus to decay exactly together. / The time for radiation to become harmless in all situations. / The age of a single unstable nucleus.

3. Which radiation is usually the most penetrating of alpha, beta, and gamma?

Answer: Gamma radiation.

Distractors to watch for: Alpha radiation. / Beta radiation is always stopped by air instantly. / All three have exactly the same penetrating power.

Starter Set

Begin with one strong interactive from each strand before browsing the full chapter.

Atomic nucleus

Rutherford'S And Thomson'S Atomic Model

Explore Rutherford'S And Thomson'S Atomic Model as an interactive EJS simulation for modern physics.

Study Atomic nucleus

Radioactive decay

Radioactive Decay Model

Explore Radioactive Decay Model as an interactive EJS simulation for modern physics.

Study Radioactive decay

Radiation

Geiger Reader App ( Requires A Geiger Reader Detector To Work Properly)

Explore Geiger Reader App ( Requires A Geiger Reader Detector To Work Properly) as an interactive EJS simulation for modern physics.

Study Radiation

Nuclear evidence

Bragg'S Law Simulator For N =1

Explore Bragg'S Law Simulator For N =1 as an interactive EJS simulation for modern physics.

Study Nuclear evidence

Nuclear systems

Nuclear Binary System Simulator

Explore Nuclear Binary System Simulator as an interactive EJS simulation for modern physics.

Study Nuclear systems

Adaptive Suggestion

If this chapter feels hard, study the first few interactives and use the concept checks until your streak improves. If it feels easy, jump to resources with videos or OSPSG links and explain the model evidence in your own words.

Back to chapter map

1. Rutherford'S And Thomson'S Atomic Model

ejss_model_rutherfordwee1

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2. Rutherford'S Atomic Model

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3. Radioactive Decay Model

ejss_model_decaychangeNwee

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4. Dice Rolling Model

ejss_model_decaychangeNweedice

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5. Dice Rolling Model

ejss_model_decaychangeNweediceSLS

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6. Radioactive Decay Model

ejss_model_decaychangeNweethreestate

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7. Three State Nuclear Decay

ejss_model_ThreeStateNuclearDecaywee2

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8. Three State Nuclear Decay

ejss_model_ThreeStateNuclearDecaywee2 / index_es

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9. Three State Nuclear Decay

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10. Intro Page

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11. Intro Page

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12. Intro Page

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13. Three State Decay Theory

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14. Intro Page

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15. Geiger Reader App ( Requires A Geiger Reader Detector To Work Properly)

ejss_model_Geiger_reader

Explore Geiger Reader App ( Requires A Geiger Reader Detector To Work Properly) as an interactive EJS simulation for modern physics.