How Quickly Does an Electron Spiral into the Nucleus in Classical Physics?

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SUMMARY

The discussion focuses on the classical physics of an electron spiraling into the nucleus of a hydrogen atom. It establishes that the rate of radiation due to acceleration is given by the formula dE/dt = - (e²a²)/(6πε₀c³). The derived rate at which the electron spirals into the nucleus is dr/dt = - e⁴/(12π²ε₀²r²mₑ²c³). The problem also prompts the calculation of the time interval for the electron to reach r = 0 from an initial radius of r₀ = 2.00 x 10⁻¹⁰ m.

PREREQUISITES
  • Understanding of classical electromagnetism, specifically the radiation of accelerating charges.
  • Familiarity with the concepts of kinetic energy and potential energy in the context of atomic physics.
  • Knowledge of the constants involved in the equations, including the electron charge (e), permittivity of free space (ε₀), and speed of light (c).
  • Ability to apply conservation of energy principles to atomic systems.
NEXT STEPS
  • Study the derivation of energy levels in hydrogen atoms using classical mechanics.
  • Learn about the implications of radiation reaction in classical electrodynamics.
  • Explore the quantum mechanical treatment of electron behavior in atoms for comparison.
  • Investigate the role of angular momentum in the stability of electron orbits in classical and quantum frameworks.
USEFUL FOR

This discussion is beneficial for physics students, educators, and anyone interested in the classical mechanics of atomic structures, particularly those studying the behavior of electrons in hydrogen atoms.

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Homework Statement


According to classical physics, a charge e moving with an acceleration a radiates at a rate
dE/dt = - (e2a2)/(6pi epsilon c3)

a) Show that an electron in a classical hydrogen atom spirals into the nucleus at a rate
dr/dt = - e4/ (12pi^2 epsilon^2 r^2 me^2c3)

b) Find the time interval over which the electron will reach r = 0, starting from ro = 2.00 X 10-10 m.


Homework Equations


None


The Attempt at a Solution


We are not sure how to relate energy with radius.
 
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From a purely classical standpoint you can ask:

-what is energy of a ground state electron in a hydrogen atom?

-what is the starting radius of the electron in a hydrogen atom?

-we assume, it is moving in a circle, so what is the formula for its kinetic energy?

You should be able to answer these questions and then use conservation of energy to put together a formula for the energy as a function of radius.

From there you can solve the problem.

Hope this helps!
 

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