University Physics III · Quantum Physics · 9.09
Potential barriers and quantum tunnelling
Exponential decay of psi inside a barrier and transmission near the exponential of minus 2 κ L, with kappa set by the square root of mass times the barrier height above the particle energy, so transmission falls exponentially in width but only with that square root in mass and height; alpha decay and scanning tunnelling microscopy; the estimate drops the prefactor and assumes a thick, one-dimensional, static barrier.
Course-map guide · not a complete lesson or simulationScope & orientation
What this subsection covers
Exponential decay of psi inside a barrier and transmission near the exponential of minus 2 κ L, with kappa set by the square root of mass times the barrier height above the particle energy, so transmission falls exponentially in width but only with that square root in mass and height; alpha dec…A strong response uses stopping-potential versus frequency graphs 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 stopping potential vary linearly with frequency, and what value of h and work function does the fit support?
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Does stopping potential vary linearly with frequency, and what value of h and work function does the fit support? Useful evidence includes stopping-potential data at several source frequencies, a linear fit with slope h/e and intercept minus φ/e, residuals, propagated uncertainty, and a stated range of validity.
Limits to state
This GioPhysics course map is an adaptable learning sequence, not academic credit, accreditation, or a universal university syllabus.
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This GioPhysics course map is an adaptable learning sequence, not academic credit, accreditation, or a universal university syllabus. Third-semester content is the least standardised of the introductory sequence: departments place oscillations, waves, optics, and thermal physics differently, and the modern-physics units here are a bounded survey rather than a complete course in relativity, quantum mechanics, atomic, nuclear, or particle physics. 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.
Model, evidence, and boundary
What is the strongest test of a claim about Potential barriers and quantum tunnelling?
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 Potential barriers and quantum tunnelling?
Quick check
Test the reasoning, not recall
What is the strongest test of a claim about Potential barriers and quantum tunnelling?
Choose an answer to test the model.