Under what conditions does quantum mechanics reduce to classical mechanics?

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SUMMARY

The discussion focuses on determining the conditions under which quantum mechanics transitions to classical mechanics using the equation E=(n²h²)/(8mL²). The key insight is that the change in energy between adjacent levels, represented by ((n2²-n1²)h²)/(8mL²), must equal the thermal energy kT at 310K, which is 4.28x(10^-21). By setting n2=2 and n1=1, participants can solve for mL², noting that larger values of n2 result in larger mL² values, indicating the conditions for classical mechanics dominance.

PREREQUISITES
  • Understanding of quantum mechanics principles
  • Familiarity with the concept of thermal energy (kT)
  • Knowledge of energy level equations in quantum systems
  • Basic algebra for solving equations with multiple variables
NEXT STEPS
  • Explore the implications of the quantum-classical transition in various physical systems
  • Study the derivation and applications of the energy level equation E=(n²h²)/(8mL²)
  • Investigate the significance of thermal energy in quantum mechanics
  • Learn about the role of quantum numbers in determining energy levels
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Students and researchers in physics, particularly those studying quantum mechanics and its relationship to classical mechanics, as well as educators looking to explain these concepts effectively.

amberbarton
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Homework Statement


"At 310K thermal energy kT=4.28x(10^-21). Use the equation you derived above (which I worked out to be E=(n²h²)/(8mL²) )to determine under which conditions quantum mechanics reduces to classical mechanics."
The hint was that "you need to find the value of mL² for which change in E between two adjacent energy levels is equal to kT".

Homework Equations


E=kt
E=(n²h²)/(8mL²)

The Attempt at a Solution


I'm not quite sure how to start here, the only thing I've managed to do so far is:

((n2²-n1²)h²)/(8mL²)=4.28x(10^-21)

I'm not sure what to do with so many unknowns, or what the question is actually asking me to calculate!
 
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amberbarton said:
...


I'm not quite sure how to start here, the only thing I've managed to do so far is:

((n2²-n1²)h²)/(8mL²)=4.28x(10^-21)

I'm not sure what to do with so many unknowns, or what the question is actually asking me to calculate!

Assuming the above is correct let n2 = 2 and let n1 = 1. Now solve for mL^2.

Larger values of n2 will yield larger values of mL^2 which you should point out.
 

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