Recent content by PenKnight

Yep your right. I was trying to show what the spin operators pulls out for a particular pairing but mucked up in notation. I think going through a couple of examples may get my head around this. Here the first one with N = 3 and considering periodic boundary condition...

Homework Statement Same problem as this old post https://www.physicsforums.com/showthread.php?t=188714 What I'm having problems with is determining the H_{ij} components of the Hamiltonian of a one dimension N site spin chain. And then getting out somehow energy value to prove...

I made a mistake by saying that both photons will have to hit the slit at the same time.I completely disregarded the wave behavior of light. How can you tell if two photons are arriving at the slit at the same time? It would be just one larger photon = superposition of the two, and it's this...

I asked becuase you assume ( I assume that you assumed :S) that the all photons will be dectected as they hit the photomulitpler. I used a photomulitpler too in one of my experiments and been told that there a dead time for this device. It's the time required for charging up to dectect the...

I like to try and help. How do you know you are detecting more than one photon?

Just a bit confused/ need confirmation of what's happening. We shine light at the double slit and see interference patterns. Place two opposite 1/4 waves plate, so that we have which way information, in front of the slits. This causes the pattern to disappear. 1. Under what condition does...

Homework Statement Considering a cylinder of radius, R, and length D with uniform charge density p containing a spherical cavity of radius R/2. Find the field in the cavity. The cavity sits on one side of the cylinder so that it's diameter spans from the concave face of the cylinder to the...

Yea, I think I got a little confused since my book is a mess. I had the question and answers messed up. The continuity Rule should of been f(x) not df and in your exact words "f(x,y), is continuous at (0, 0) if and only if its limit, as (x, y) goes to (0, 0) is f(0,0)." I took that from another...

Homework Statement f(x,y) is a hybrid function 1. ( ( xy+x )^3 ) / ( x^2 + xy ) when (x,y) not equal to (0,0) 2. 0.........when (x,y) = (0,0) Is this function continuous at the origin? Homework Equations ...lim...df |(x,y) = df(0,0) (x,y)->(0,0) The Attempt at a Solution...

Homework Statement I was thinking about the 3 polarizers experiment where you have them angled 45 degree to each other and the first and third are perpendicular. With 2 polarizer angles 90 degree to each other, no light passes through. But with a third one inserted between them at a angle of...

Hi all. My first post. I hope I posted in the right section. I watched ep 1 of these old videos lecture by Richard Feynman and wondering if it's still valid. Or should I take on his ideas and formula my own understand from all possible views. Or how should I learn this subject. http://...