# Homework Help: Structural Models of the Atom

1. Aug 13, 2009

### define_normal

1. The problem statement, all variables and given/known data
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.

2. Relevant equations
None

3. The attempt at a solution
We are not sure how to relate energy with radius.
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

2. Aug 13, 2009

### jpreed

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!