University Quantum Mechanics I · The Infinite Square Well · 6.04
Excited states, half-wavelengths, and nodes
ψₙ fits n half-wavelengths into L and carries n - 1 interior nodes, exactly like a string clamped at both ends.
Course-map guide · not a complete lesson or simulationScope & orientation
What this subsection covers
ψₙ fits n half-wavelengths into L and carries n - 1 interior nodes, exactly like a string clamped at both ends.A strong response uses snapshots of |ψ(x, t)|² across one beat and states where the model stops being reliable.
Reasoning checklist
Evidence, assumptions and limits
Assumptions to state
State the system, observable, approximation, and conditions held fixed before using a model.
Evidence to collect
Does a two-term superposition oscillate at angular frequency (E₂ - E₁)/ℏ, and does a many-term packet return at the revival time 4mL²/(π ℏ)?
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Does a two-term superposition oscillate at angular frequency (E₂ - E₁)/ℏ, and does a many-term packet return at the revival time 4mL²/(π ℏ)? Useful evidence includes snapshots of |Ψ(x, t)|², ⟨x⟩(t) with its fitted period set against 2 pi ℏ/(E₂ - E₁), |cₙ|² and ⟨H⟩ shown numerically constant, and the revival traced to level gaps that are integer multiples of E₁.
Limits to state
This GioPhysics course map is an adaptable learning sequence, not academic credit, accreditation, or a universal university syllabus.
Read the complete note
This GioPhysics course map is an adaptable learning sequence, not academic credit, accreditation, or a universal university syllabus. It is a first dedicated quantum-mechanics course, distinct from University Physics V, which covers quantum mechanics alongside atomic, nuclear and particle physics in twenty units: this course is narrower, slower, and teaches the linear algebra it needs rather than assuming it. Hydrogen appears here as an introduction, with the full radial derivation belonging to a second course. A midterm examination is assumed around week 8. Follow your institution's published scope, notation, laboratory programme, and assessment rules. A result should be checked against units, signs, limiting cases, and the conditions under which its model was derived.
Diagram & examples
Work the claim before choosing an equation
Interactive concept map
Follow the model from claim to evidence.
ψₙ fits n half-wavelengths into L and carries n - 1 interior nodes, exactly like a string clamped at both ends. A node is a zero of ψ, not a barrier a particle cannot cross, and |ψₙ|² does not move in a stationary state.
Model, evidence, and boundary
What is the strongest test of a claim about Excited states, half-wavelengths, and nodes?
modelModel, evidence, and boundary turns the stated idea into a representation that can make a prediction.
Example questions
Try the reasoning before revealing the structure.
What is the strongest test of a claim about Excited states, half-wavelengths, and nodes?
Quick check
Test the reasoning, not recall
What is the strongest test of a claim about Excited states, half-wavelengths, and nodes?
Choose an answer to test the model.