Recent content by wdednam

Okay, I managed to get the answer. For those who are interested, the calculation should be done at T = 0. Since the electrons are within kT of Ef, and Ef >> kT, the density of states is just D(Ef) = 3N/2Ef which is constant so it can come out of the integral in the numerator (the integral from...

Homework Statement Show that the fraction of electrons within kT of the fermi level is equal to 3kT/2Ef, if D(E) = E^1/2. Homework Equations f(E) = 1 / ( exp(E-Ef)/kT + 1 ) fermi distribution N = integral from 0 to inf of D(E)f(E)dE = total no. of electrons The Attempt at a...

Hi Fabsuk, I know this answer is a little late in coming, but I only came across your post now. The reason I only came across it now is because I'm having problems with a similar problem. The CsCl lattice constant is just the edge length of its conventional unit cell (a BCC structure), that...

Hi there, Thanks for the additional example! Let me just check with you if the expression I wrote down for the invariant mass of the left side of the reaction (which I took to be in the lab frame) is correct: {Ep + (Ep2 + P2c2)1/2}2 - {(\vec{P}c)}2 where Ep = rest mass energy of a...

Yes, I was definitely wrong when I said that the proton and neutron pick up no momentum in the lab frame, thank you very much for pointing that out to me and also insisting that I understand it right. It's in the centre of momentum frame where the total momentum of the proton and neutron is...

Hi there, Your first answer is definitely right. But then, why did you substitute omega = 2pi f and k = 2pi/lambda in the expression for the phase velocity? When I substitute the expression you were given for omega and divide it by k I get v_phase = 1/2 v. I don't think f lambda equals...

Thank you, now I understand it much better. I didn't know that the expression you gave me is true no matter what reference frame I use. I read something on the internet about it being invariant under the Lorentz transformation in Special Relativity. I was exposed to Special Relativity very...

Thank you very much Malawi Glenn! You are turning out to be a real life saver. Ok, I just want to check that I understood the physical situation properly. I think what happens here is that the centre of mass of the system is the same in the lab frame as in the centre of mass frame? So, because...

Another Nuclear Physics problem: Minimum photon energy for deuteron dissociation Homework Statement What is the minimum photon energy necessary to dissociate a deuteron. Take the binding energy to be 2.224589 MeV Homework Equations \gamma + 2H \rightarrow 1H + n \vec{P} = \vec{P_n}...

So, I could do the integral based on your suggestion. Here is the answer I got: F(q) = (pi/ln2)^(3/2)*R^3*rho0*exp{-q^2*R^2/(4ln2)} Thanks a lot again. wdednam.

I think that might just work, thank you. Let me try and see where it gets me, and then I'll get back to you here to let you know how it went. Thanks again! Wynand.

Homework Statement Compute the form factor of rho(r) = rho0 * exp[-ln2*r^2/R^2] where rho0 and R are constants. Homework Equations F(q) = 4pi/q \intsin(q*r)rho(r)rdr where the limits of integration run from 0 to \infty The Attempt at a Solution This is probably more of a...

Hi Malawi Glenn, Thank you very much, I used the equations you suggested and got the required result. I'm concurrently registered for Stat Mech, QM, Nuclear Physics and Solid State Phys this year and realized when I attempted this problem that I should have completed Stat Mech and QM before I...

Homework Statement Show that the mean-square charge radius of a uniformly charged sphere (with radius R) is < r^2 > = 3*R^2 / 5 Homework Equations < r^2 > = \int \varphif* r^2 \varphii dV \varphif* = exp(-i q dot r) \varphii = exp(i q dot r) where q = kf - ki...

Hi again, I found the solution. If you are interested in seeing it, send me a message and I'll give you the link. (I don't think it is within forum rules to post it here) Thanks to everyone who started thinking about this problem and was going to get back to me later. Cheers.