i have little questions which make me banging my head against the wall over the last few days.
now, before too many walls collapsed :
1. can anyone direct me to an easy reference which explain how to calculate demagnetization factor N for simple geometries (such as long cylinder, thin...
i have been reading articles on molecular assemblies and dna design.
my question is: if we take one simple living cell, and using molecular assembly we can create exactly the same copy of that cell (precisely to the atomic level), then will the cell be alive?:bugeye:
thanks.
in deriving quantization of flux in superconductor ring, the momentum of cooper pair p:
p=\hbar\nabla\theta=e^*(\Lambda J_s + A)
then integrate around the ring,
\hbar\oint\nabla\theta dl=e^*\oint(\Lambda J_s + A)dl
using stoke's theorem and integrate sufficiently deep in the ring where...
i just want simple explanation of this.
velocity v is a function of r and t.
then my professor, in order to derive relationship of something, he wrote:
\frac{dv}{dt}=\frac{\partial v}{\partial r}+\frac{\partial v}{\partial t}
then assuming small spatial variation,
\frac{dv}{dt} \approx...
1. is MgB2 brittle? can we draw it like wire and wind it up make a coil/electromagnet with it?
2. liquid nitrogen boils at 77K and freezes at 63K. most superconductor experiments use liquid nitrogen, so does it mean most applications use this temperature range (eg. for squid)? what about...
in a book says cooling by demagnetization can be explained in terms of reduced entropy.
As far as I know, entropy is associated with order. More order we have (i.e. more spin alignment), then less entropy S. Demagnetization results in disorder, since spins are more disorder, thus higher...
i think magnetic susceptibility xm=M/H is contant and independent of the units we are working with.
in different refferences, they sometimes quote mks or cgs units which gives different value of Xm. It confuses me. Is Xm units dependent?
for example Xm for oxygen is about 10^-4 in cgs...
in electrodynamics, we have magnetization M.
the other quantity associated with free current is H.
i haven't seen a book that gives the name to H. what is the proper name assign to H?
paramagnetism is a many body effect.
iron when heated up to its crtitical temperature will become paramagnetic of course.
paramagnetic is in fact due to orbital overlap!
when one unpaired orbital of an atom overlaps with its neighbouring atom, these two unpaired orbital will merge into...