Recent content by Gogsey

I apologize. I'm not sure myself what q is. It just says q in the 111 direction, so I'm assumeing q is 111. Sorry, was what yes we need to do all 8 combinations, or yes yes we care only about the 111 direction? The question does say that we need to sketch the dispersion relaions for the...

Turns out there should be 9 equation, but 6 of them are 0. Rge matris elements are, movement of an atom in x directio, what is the restoring force in x-direction. This is the same for xy,xz,yx,yy,yz,zx,zy,zz. xx, yy, zz are down the diagonal of the matrix. the others would be in there...

I guess that's it. Would it be (3/4)*sqrt(3)? There are also vectors (a) in all 8 combinations of +/-1/2,+/-1/2,+/-1/2 as well. Does it mean that we have to compute all the dot product for q and a with all 8 combinations? Or since we only care about the 111 direction, do we only do this for...

The distance between the 2 atoms is sqrt(3)/2 and the vector is from 0,0,0, to 1/2,1/2,1/2. So we have q dot a(the vecor given above) and q is the 111 direction.

Its a vector dotted with a length sqrt(3)/2. Vector 1/2,1/2,1/2,

So, if we have an atom at 0,0,0 and one at 1/2,1/2,1/2, and with bond length sqrt(3)/2 and are looking along the 111 direction. If we wanted to cmpute the dot product, we would do 1/2*sqrt(3)/2 + 1/2*sqrt(3)/2 + 1/2*sqrt(3)/2 = 3sqrt(3)/4? Its q dot a, and q along 111 direction. a =...

If someone says that you have to take the dot product of q*a and a is a length, and q is the 111 direction, or alonfg the 111 direction. What does that mean. Is it simply 111 dot length a. We have a exponential function to the power q dot a and want to know what to do.

The picture is a bcc lattice with all the atoms connected to each other.m Now ere onlt consideruing the effects of moving each atom on the centrakl atom. So applying a force in each dimension, and seeing what happens to the atiom in the centre of the cube. So put a force in the x direction...

This not so much of a homework proble, but something I need to visualize and understand to do a homework problem. If theeres and atom at x,y,z = 0, and one located at x,y,z, = 1/2 and we pull second atom from its posistion with a force F in anyone of the x,y,z directions, what are the...

Hi, So I have to find the dynamical matricx of a bcc lattice considering only nearest neighbours. Its like if the nearest neighbours were all attached to the atom in question by springs. So first we need the equations of motion for the lattice. There are 8 nearest neighbours, so the...

Hi, So I figured out what I'm supposed to do. Using the given equation, plus 2 other equations we that we were given, and then using another equation and plotting them on a graph we can see that where the 2 functions cross is the allowed values for beta. We have use MATLAB for this...

Consider an asymmetric planar waveguide with nf=1.5, ns=1.47, nc=1.0. Determine the allowed values of beta for the TE modes in a waveguide with thickness h=7 micrometers. Assume the excitation wavelength is 1 micrometer. Our prof gave us this equation; Beta = (Ko2nf2-Kf2)1/2 Ko...

Hi Thanks, yeah all we had to do was square the Fresnel amplitude reflection coefficient to get the power reflection coefficient and use 1-R2 to get the Fresnel power transmission coefficient.

Hi, I'm doing a question using the Fresnel power coefficients, not the Fresnel amplitude coefficients. We can use MATLAB for this, but we are given a fixed angle of incidence of 45 deg so its really just one calculation, as opposed to an earlier question where the angle varied between 0 and...

What considerations would a lens maker need to take into account when designing a lens? So on top of the chromatic aberrations, glass type and focal length, I have: Lens Thickness Magnification Resolving Power Radius of Curvature Shape(ie cylindrical, spherical, plane) Type(ie convex...