How Do I Solve Physics Homework Problems 21, 22, 23, and 24?

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The discussion focuses on solving specific physics homework problems, particularly problems 21, 22, 23, and 24. For problem 22, the user is unsure about the value of n in the Bohr radius formula, while for problem 23, they calculate energy but need to convert it to joules. A response provides formulas for calculating the radius and energy levels, emphasizing the importance of correctly determining the reduced mass. Additionally, problem 21 involves calculating work for an electron transitioning to a higher energy level, and problem 24 relates to kinetic energy. The user expresses intent to attempt the problems after receiving guidance.
Spectre32
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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 believe 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
 

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Wow, I had that exact same problem on one of my QM tests...

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

Make sure to calculate \mu 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.
T = \frac{p^2}{2m}

cookiemonster
 
Awsome i'll take a crack at e'm and we'll see where at leaves me.
 
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