Modern Physics · Chapter

Quantum Physics

Use simulations to make photons, spectra, semiconductors, lasers, and quantum ideas inspectable.

Learning Path

Checkpoint 1: Photoelectric effect

Photons and Threshold Frequency

Use photoelectric simulations to connect photon energy, frequency, intensity, threshold frequency, and emitted electrons.

Checkpoint 2: Wave-particle duality

Interference from Quantum Objects

Explore double-slit models to see how interference patterns challenge purely particle-only explanations.

Checkpoint 3: Atomic spectra

Energy Levels and Spectral Lines

Use Bohr and spectrum models to connect transitions, photon energy, and emission or absorption lines.

Checkpoint 4: X-rays

Imaging and Absorption

Inspect X-ray spectra, absorption, and imaging models to connect quantum interactions with medical and material applications.

Checkpoint 5: Lasers and semiconductors

Quantum Devices

Use laser and semiconductor simulations to connect energy bands, beam profiles, and device behaviour.

Checkpoint 6: Quantum models

Beyond the Classical Picture

Explore electron clouds, spin, and entanglement models as visual entry points into modern quantum ideas.

Chapter Lens

How do quantum models explain light, spectra, matter, and devices that classical ideas cannot fully describe?

Light and matter can show both wave-like and particle-like behaviour depending on the experiment.
Atomic spectra provide evidence that electrons occupy discrete energy levels.
Quantum ideas support practical technologies such as X-ray imaging, lasers, semiconductors, LEDs, and modern sensors.

Misconception Watch

Increasing intensity is not the same as increasing photon energy; frequency matters for photoelectric emission.
Energy levels are discrete, so spectra are evidence for quantised atomic structure.
Wave-particle duality is not simply switching between two everyday objects; it is a model-dependent way to explain observed behaviour.

Chapter Concept Checks

1. In the photoelectric effect, increasing light intensity below threshold frequency does what?

Answer: It still does not eject electrons because each photon has insufficient energy.

Distractors to watch for: It immediately ejects electrons because total brightness is all that matters. / It changes the metal into an insulator. / It removes the need for photons.

2. Why are atomic emission spectra line spectra rather than continuous rainbows?

Answer: Electrons transition between discrete energy levels and emit photons with specific energies.

Distractors to watch for: Atoms emit every possible photon energy equally. / The spectrometer deletes most colours randomly. / Only red light can be emitted by atoms.

3. What does a double-slit interference pattern suggest about quantum objects?

Answer: They can show wave-like behaviour even when detected as individual events.

Distractors to watch for: They are always large classical balls. / They never interact with screens. / They have no measurable behaviour.

Starter Set

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

Photoelectric effect

Photoelectric Effect Model

Explore Photoelectric Effect Model as an interactive EJS simulation for electricity and magnetism.

Study Photoelectric effect

Wave-particle duality

Double Slit Wave Particle Duality Model

Explore Double Slit Wave Particle Duality Model as an interactive EJS simulation for waves and optics.

Study Wave-particle duality

Atomic spectra

Emission Absorption And Continuous Atomic Spectrum And Energy Levels Of Hydrogen Gas Si...

Explore Emission Absorption And Continuous Atomic Spectrum And Energy Levels Of Hydrogen Gas Si... as an interactive EJS simulation for modern physics.

Study Atomic spectra

X-rays

X Ray Imaging Physics

Explore X Ray Imaging Physics as an interactive EJS simulation for modern physics.

Study X-rays

Lasers and semiconductors

Laser Beam Profile

Explore Laser Beam Profile as an interactive EJS simulation for modern physics.

Study Lasers and semiconductors

Quantum models

Quantum Wave Packet

Explore Quantum Wave Packet as an interactive EJS simulation for waves and optics.

Study Quantum models

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. Photoelectric Effect Model

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2. Photoelectric Effect Simulator

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3. Photoelectric Effect Model

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4. Photoelectric Effect Model

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5. Double Slit Wave Particle Duality Model

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6. Double Slit Wave Particle Duality

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7. Emission Absorption And Continuous Atomic Spectrum And Energy Levels Of Hydrogen Gas Si...

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8. Emission Absorption And Continuous Atomic Spectrum And Energy Levels Of Hydrogen Gas Si...

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9. Bohr Model Of The Atomic Energy Levels

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10. Bohr Model Of The Atomic Energy Levels

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11. Differential Absorption Of X Rays

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12. Differential Absorption Student Activities

ejss_model_DifferentialXRayAbsorbtionwee / Differential_Absorption_supplemental / Differential Absorption - Student Activities

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13. X Ray Spectrum

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14. X Ray Spectrum Technical Notes

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15. Blackbody Radiation Spectrum

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16. Atomic Spectra Of Hydrogen And Red Shift

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17. Blackbody Radiation Spectrum

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18. Differential Absorption Student Activities

ejss_src_DifferentialXRayAbsorbtionwee / Differential_Absorption_supplemental / Differential Absorption - Student Activities

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19. X Ray Spectrum Technical Notes

ejss_src_XRaySpectrumwee / XRay_Spectrum_supplemental / XRaySpectrumTechNotes

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20. X Ray Imaging Physics

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21. New

ejss_model_XRayImagingwee / Imaging_Supplemental / imaging_intro

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22. New

ejss_src_XRayImagingwee / Imaging_Supplemental / imaging_intro

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23. Laser Beam Profile

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24. Laser Beam Profile EXERCISE 2: THE TEM 00 MODE: A CONTOUR PLOT

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25. Laser Beam Profile EXERCISE 3: THE KNIFE EDGE PROFILE

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26. Laser Beam Profile EXERCISE 4: FIT EXPERIMENTAL DATA TO THE MODEL KNIFE EDGE PROFILE

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27. Laser Pumping

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