# Tag Info

1

Isn't it just a convention you have to choose once and for all. It's all about how to pass from Maxwell to lumped element circuits. Especially, I can choose the two different conventions (all quantities are vectorial in the following) $$E=\pm\nabla V$$ since I didn't choose my field-to-potential rules yet. Usually one chooses to conform to the classical ...

0

Partial answer here about what the author means by flux: We now introduce the flux $\phi_n$ of a node $n$ which is defined by the time integral of the voltage measured along the path connecting the node to the ground on the spanning tree. (Defined a few pages prior to 363.) It then seems $\dot\phi$ is voltage as we would normally define it.

4

The heat that makes a filament lamp glow is derived from electrons bashing into the lattice of atoms in the filament and transferring energy to them. The kinetic energy of the electrons becomes vibrational energy of the lattice, and this is exactly what heat is. However the interaction of electrons with the lattice is also what resistance is, and ...

2

$|GS\rangle$ is the ground-state of $H_{MF}$. As can be verified: ...

0

Once produced, any magnet does not give nor take energy from the environment. The magnet field lines are closed and could only be bend (to work with some physical model). Any magnet, a permanent as a electric as a superconducted, works like a spring in mechanical systems. This you can see by the way that an electric or a permanent magnet from the same ...

3

The gravitational analogue of magnetism is called "gravitomagnetism" (and the general mathematical analogy between Maxwell's equations and gravitation in general relativity is called gravito-electromagnetism), which deals with the gravitational interactions of currents of mass/energy, just as magnetism deals with interactions of currents of charge. According ...

0

I think the basic problem here is that a magnetic gradient is required for levitation, whereas the Earth's magnetic field is very close to uniform on the scale of any human-scale crafts. Try using the right-hand rule to figure out the direction of the magnetic force from a uniform magnetic field at two points on opposite sides of a circular current loop ...

2

The energy you supply by the force is transformed into changing the flux tube configuration. Microscopically this means that certain parts of the superconductor go from superconducting to "normal" in a small areas (flux tubes) to allow the magnetic flux through and the energy supplied is used to rearrange these regions. In superconductors that stay fixed ...

0

Ah, this is a classic and rather tragic issue in most statistical-mechanics books. I won't talk about superconductivity, but the general case of magnetic systems. The problem is thermodynamics as it is, was formulated for fluid systems for which pressure and volume were observables and could be manipulated. In that case, say I calculated the partition ...

Top 50 recent answers are included