Recent content by Dizzle

Tidal locking takes some time though right, so if the moon wasn't that old, it could still rotate with respect to the planet, right?

Maths. Do as much damn maths as you can. Get ahead of your classmates and those in the year above you. At university take maths first and physics second - you can go from maths to physics much more easily than the other way round. Brian Greene's The Elegant Universe is a popular physics book...

In special relativity we have the velocity 'u', being the difference in speed between two objects, from which we work out time dilation, length contraction etc. But if those objects are separated by some expanding space, but not moving with respect to that space, is there still the dilation...

My issue is the 1st of those two atyy. I guess I thought I could answer that by asking the 2nd. I understand exp(ikx) is one with definite momentum and so definite k. Im trying to understand electrons in solids, wherebye with periodic boundary conditions as stated above the derivation seems...

OK. So forgetting 'free space / free particle', can we arive at Ψ(x) = Aexp(ikx) purely from the periodic BCs I wrote above? Thanks again :)

ZikZak: Ok so that explains why a particle won't have both terms, because it has had its momentum measured so it must be going in one direction or the other, determined by k. But does that mean, for the 1D SE, with V=0 and periodic boundary conditions Ψ(0) = Ψ(L) and dΨ/dx (x=0) = dΨ/dx...

If you solve the 1D time independent schrodinger equation for a system with V(x)=0, you get a solution like: Ψ(x) = Aexp(ikx) + Bexp(-ikx) Applying certain boundary conditions would give you the solution to the Simple harmonic oscillator or infinite well etc. But I often see the...

Hmm yes I think you are right given what I have told you, but I think I have misunderstood something and given you wrong information. I think my problem was with N. I think N is not the total electrons in the metal, but just the number per unit cell, which means N/L does give me the number...

Yes that makes more sense, but if you derive the Fermi Energy in 1D, you will start with the density of states function in 1D which has an "L" in it, which appears to relate to the periodicity of the lattice as you say. However, when you do derive the Fermi Energy by integrating the density...

Free Electron Model: Why periodic boundary conditions and what is "L"? Right, hello! The quantum free electron model for electrons in solids (in One dimension) says we need to use periodic boundary conditions such that if Y(x) is the wavefunction, then Y(x) = Y(x+L). Where L seems to be...