Recent content by andrepd

Hi. I am going to start my 2nd year of undergraduate Physics this month. Here at my Uni you can apply, for no extra charge, to one extra class per semester, in any field of study. I regret I didn't do it last year, cause I was lazy, but now I really want to. Thing is, I have no idea what to...

You. are. wrong. I don't know if you still haven't understood what I needed, but you nevertheless made several mistakes. It's not, according to the very wikipedia article you linked me to, vg = c2/v, where vg is the group velocity, vp is the phase velocity, and v is the particle velocity. I...

I know that, however, that is now what I was looking for. I know that the phase velocity equals ω/k. Again, I wanted to know how I can prove this relation \omega/k=\sqrt{\frac{k^{2}c^{2}+m^{2}c^{4}/\hbar^{2}}{k^{2}}}=c^{2}/v I've figured it now. For the record...

This yields the the same result for the *group* velocity. However, I am having trouble with the derivation of the *phase* velocity, \omega/k, which, in the context of matter waves, is not equal to v, but rather to c^2/v.

Care to explain then? dω/dk=d/dk(\sqrt{k^{2}c^{2}+m^{2}c^{4}/\hbar^{2}})=1/2*(k^{2}c^{2}+m^{2}c^{4}/\hbar^{2})^{-1/2}*2kc^{2}=\frac{k}{\omega}c^{2}=\frac{v}{c^{2}}*c^2=v This was my thought process. Care to point my mistake? EDIT: This, however, presumes previous knowledge that vf=c^2/v. Hence...

If I'm not mistaken, differentiating our expression for ω(k) yields vg=(k/ω)c^2, which, if we know beforehand that the phase velocity equals c^2/v, can express as vg=v. However, I'm unsure how we get from vf = ω/k = \sqrt{\frac{k^{2}c^{2}+m^{2}c^{4}/\hbar^{2}}{k^{2}}} to vf=c^2/v.

Hi. Today I sat my final first year Modern Physics exam. It went very well, however I got stuck in one question. It asked (i) to prove the following relation for the matter wave \omega^{2}=k^{2}c^{2}+m^{2}c^{4}/\hbar^{2} and (ii) to obtain the group velocity and phase velocity of a matter wave...

I don't think I did commit grammatical errors in my OP. Maybe you mistaked to (eigentime) with the word to (preposition). I should have used italics, my bad. I see. I have looked deeper into it and I seem to have sorted it out. My initial assumptions were incorrect. Thanks for the help.

I'm confused. If t=γ*t0 and L0=γ*t how does the equation x=v*t hold for x0=v*t0, for constant velocity (Let t0 be the time in the stationary reference frame and t the moving frame, the same for length)? Then v would be equal to γ^2*v... Perhaps I'm missing something here.

Hi. I'm looking for a calculator similar to the Casio fx-911es plus, but with programming capabilities,or at least simply a small expression that I can write and save to. The fx-911 is mostly good, but it annoys me that it clears memory on Power off (minus the 8 variables). I used to have...