Recent content by yxgao

Hi! Two (distinguishable) non-interacting electrons are in an infinite square well with hard walls at x=0 and x=a, so that the one particle states are \phi_n(x)=\sqrt{\frac{2}{a}} sin(\frac{n\pi}{a}x), E_n=n^2K where K=\pi^2\hbar^2/(2ma^2) My question is what are the spins and space-spin...

I made a mistake in my equation. The correct one is this: f(\theta)=\int r e^{\frac{-r^2}{a^2}} sin(kr) dr where a is a constant. This equation gives the scattering amplitude for spherical symmetry. If I write this as: f(\theta)=\int r^2 e^{\frac{-r^2}{a^2}} \frac{sin(kr)}{r} dr...

Hi, can someone help me with this problem? A hydrogen atom is in the 2P state with n=2, l=1, m=1. It emits a photon and makes a transition to the 1S state (n=1, l=0, m=0). The question is what is the probability distribution of the direction (\theta , \phi) of the emitted photon? The...

Hi, I'm confused once again about a spin problem. The nuclei in a hydrogen molecule are identical protons. Spin states can be ortho (triplets) with parallel spin or para (singlets) with antiparallel spin. What are the three lowest energies for the para and ortho hydrogen molecules...

Hi, I'm trying to evaluate the following integral to calculate the scattering cross section for a spherically symmetrical potential e^{\frac{-r^2}{a^2}}? f(\theta)=\int r e^{\frac{-r^2}{a^2}} sin(kr) dr where a is a constant. What is the easiest way to evaluate this? I was able to get...

Hi, I have a question as follows. For an infinite solenoid with magnetic flux \Phi, for what values of \Phi "is the quantum mechanical motion of an electron constrained to stray far from the solenoid exactly the same as it would be if \Phi were zero"? Solution: \Phi = n \Phi_{o} with n =...

What is the ratio of the radii of muonic hydrogen to hydrogen? Muonic hydrogen consists of a proton and \mu^{-}. How do you calculate this??

Thanks for your detailed explanation. How do you go from the last expression in the third to last line to the second to last line? Why do you only have 7 and not 8 terms in the parenthesis? Thx

Why does the half of a harmonic oscillator potential allow only odd values of n? Thx

Hi, I'm having problems with this quantum mechanics problem. This is from a practice final I found online somewhere. A particle of spin S has either spin S=0 or spin S=1. It decays into two electrons, and the spin of the two electrons is that of the original particle. The electrons come out...

That's what the solution said. I don't fully understand the theorem. Is there any way you can explain this better, in context of the problem? Thanks a lot for help!

Thx guys for your posts. This was the only one that made me laugh, but I had already found it online. I guess there aren't too many good ones, but the stories you posted were really funny.

I was wondering if someone could help me explain this problem. In a baryon, two quarks are in l=0 and one quark is in the l=1 state. Quarks are spin-1/2 particles. What values can the total angular momentum take? I know the answer is 1/2, 3/2, and 5/2, but I'm confused about how they...

Does anyone know any laser jokes? I'm doing a short presentation on laser diodes and thought it might be fun to include a refreshing page of jokes near the end. I found a few on Google, but none were very funny.

Thanks! I really appreciate it! \lambda \mu