Recent content by liorda

oops. From now on, I'll never try to guess root. Quadratic equation, we meet again. Thanks guys.

Homework Statement I=\int_{-\infty}^{\infty} { dx \over {5x^2+6x+5}}Homework Equations The residue theorem.The Attempt at a Solution I can't use the residue theorem since the denominator has real zeros. How should I solve this?

Homework Statement prove, using mathematical induction, that the next equation holds for all positive t. \sum_{k=0}^n \dbinom{k+t}{k} = \dbinom{t+n+1}{n} Homework Equations \dbinom{n}{k} = {{n!} \over {k!(n-k)!}The Attempt at a Solution checked that the base is correct (for t=0, and even for...

any moderator, please move my question to quantum physics forum. thanks.

Homework Statement consider the state (\frac{1}{2}, \frac{1}{2}, \frac{1}{\sqrt{2}}) in L_z basis. If L_x^2 is measured and the result of 0 is obtained, find the final state after the measurement. How probable is this result? The Attempt at a Solution I'm not sure if the state is...

Hi Mindscrape, thanks for answering. I didn't normalize psi_1, because the expression is a superposition of two eigenstates of a particle in a infinite box (it's just a sum of two sines). I compared the coefficients of sin(a) cos(b) = \frac{1}{2} \left[ sin(a+b)+sin(a-b)\right] to the well...

Homework Statement http://img379.imageshack.us/img379/1864/screenshothw4pdfapplicamd7.png Homework Equations H|\psi > = E_n |\psi > The Attempt at a Solution About part 1 of the question: I can find the eigenfunctions of psi_1 by comparing coefficients with the well known...

I stand corrected. although I did say |psy|^2 is the density of probability.

kreil and EngageEngage: thanks a lot! I now get that the observation value for the radial momentum is 0. does it have a physical meaning? is there any way of anticipating that result by looking at the wavefunction? and should I even try to search physical meanings in quantum mechanics...

the r^2*sin(t) is the |Jacobian| isn't it? I thought it should only be added when making a transformation between Cartesian and spherical coordinates, i.e \int\int\int dxdydz = \int\int\int r^2 sin(\theta) d\phi d\theta dr... although the r^2 sin(t) will solve the integral convergence problem...

Are you sure? Can I just disregard the inf in the equation?!? thanks again for answering.

Hi Josh, Thanks for answering. I ended up with this: < \psi |p_r| \psi> = \frac{N^2 \hbar}{i} \int_0^{\pi}cos^2(\theta)d \theta \int_0^{2 \pi}d \phi \int_0^{\infty} \left( \frac{d}{dr}+ \frac{1}{r} \right) \right e^{-2(r/R_0)^2} dr My problem is with \int_0^\infty \frac{1}{r}...

I think it has no dimensions. p(r) = |\psi|^2 is the density of the probability of finding a practical in a specific location. But maybe I'm wrong

Homework Statement My wavefunction is \psi (r, \theta, \phi )=N cos(\theta) e^{-(r/R_0)^2}. I need to calculate <p_r> and \Delta p_r where p_r is the radial momentum. Homework Equations I think i know p_r=\frac{\hbar}{i} \left( \frac{d}{dr}+\frac{1}{r} \right) . The Attempt at a...

thanks for answering. You helped me "getting it" :) I think our normalization factors are different. I know that F[e^{-|x|}]=\frac{1}{\pi (\omega^2 +1)}, so if a,b>0 (i assume it, since it's the only way to get to the following result) i can write F[e^{-\frac{a}{b} |x|}]=\frac{b}{a}...