Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Need help with these last few problems

  1. Apr 21, 2004 #1
    Alright i scaned in my HW but it didn;t work soo all of my work is not there. Anyways, I need some help with #22 and #23. For 22 i started of with Bhors R = n^2/Z(.5929e-10( but i didn't know what to use for n. THen for 23 I used En=- 1^2/4^2(13.8eV) and got -.8625eV i belive all i need to do is convert it to J's/ Also 21 and 24 i need to g3et get but i'm super lost on those.

    Thanks for any help
     

    Attached Files:

  2. jcsd
  3. Apr 22, 2004 #2
    Wow, I had that exact same problem on one of my QM tests...

    [tex]r_n = \frac{n^2}{Z} \frac{m_e}{\mu} a_0[/tex]
    and
    [tex]E_n = -\frac{Z^2}{n^2}\frac{\mu}{m_e} E_0[/tex]

    Make sure to calculate [itex]\mu[/itex] correctly. And you're looking for the first state in 22, so n = 1.

    21. Calculate the work required to elevate them to the n = 5 level. Then just use the kinetic energy formula.

    24.
    [tex]T = \frac{p^2}{2m}[/tex]

    cookiemonster
     
  4. Apr 22, 2004 #3
    Awsome i'll take a crack at e'm and we'll see where at leaves me.
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook