labview1958

I am interested in the following formula regarding MAGLEV. It is a relationship between drag force and lift force. Drag Force=k*Lift Force where k = ω/v and ω = 2/(μσ Δ) • where μ = permeability of free space • v = velocity of conductor/magnet • σ = conductivity of track • Δ = thickness of conductor ω = characteristic velocity I have run an experiment on copper and I found that the characteristic velocity found by experiment is twice the calculated value. Since ω = 2/(μσ Δ) and (μσ Δ) is a constant, how can that be? Is the standard formula given in textbooks wrong? Where can I get more experimental data regarding MAGLEV?

Anyone interested in discussing superconductivity pinning force? Is there a better forum?

I am trying to expand the following eaquation to plain english. Can anyone help? The magnetic field on the z axis of a solenoid (in Gaussian units) is: B=[2\pi(N/L)I/c][sin A_2-sin A_1], where A_i is the angle between a line perpendicular to the axis of the solenoid at one end and a point on the z axis. If you write this in terms of z and expand, you can use Legendre polyomials to find the field off the axis and the dipole moment of the solenoid. Can someone just make this equation simpler?

I have come across a diagram, I believe describe the "pinning force" on a certain type of maglev. It looks as if the "pinning force" is similar to the electromagnetic drag force. Is my assumption valid? Here is the diagram. The superconductor is moved over a series of magnet. The forward movement is the centrifugal force.

I gather you mean a hollow sphere? The skin would be superconducting. What if it is a solid sphere?

I do not know much about Legendre Poynomials. Can you expand the equation a bit in plain english?

Is it possible to measure the pinning force. I measured the electromagnetic drag force like this. http://img102.imageshack.us/my.php?image=rotatingcoppermagnet0an.png Can the same method be used to measure the pinning force?

I noticed that a website selling superconductors had a max force of 80N for a coin size superconductor. I have once visited a superconducter lab and was told the max force of their coin size made-in-lab superconductors were 10mN. Who is right?

What I found was a hollow superconducting cylinder can act as an electromagnetic shield. Can a coin type bulk superconductor act like an electromagnetic shield?

Can a superconductor be used as a electromagnetic shield against magnetic field? Where can I find some information regarding this?

The strength of the upper magnet cannot be changed by the superconductor. The imagne of the magnet becomes stronger in the superconductor as it moves towards it. As the superconductor is fixed it cannot run away. As the upper part of the SC becomes stronger the lower part of the SC remains the same as the separation distance between the SC and the lower magnet is the same. I am a bit confused. Can someone recommend a website or book that deal with my 'problem"

Anyone out there?

positron said "a small ball-bearing ". I believe it was not that but a superconductor! Thus what you saw, was the meisnner effect between a superconductor and a magnet.

I understand the magnet is "held" in position. An external force is needed to "remove " the magnet. The superconductor will try to "resist" the magnet being "pulled" away. Thus the flux pinning will increase to it's maximum before losing to the "pulling" away force. Is this pinning force similar to the electromagnetic drag force?

In the meissner effect the magnet "floats" on a superconductor. A small magnet would actually stay in one position as if it is "pinned" there by a mysterious force. The magnet would "resist" if we try to"pluck" it from it's position. Is this "pinning force" same as the electromagnetic drag force experience by a magnet floating on a spinning copper disc?

"Get a copy of Weber's Electrodynamics by Assis." Easier said than done! I cannot find a copy where I am now! Is there a suitable website regarding that? I got my formula from a book by Mr. Moon.

Let's say I have a hollow sphere covered with a superconducting material immersed in liquid nitrogen. If a weak magnet is brought near it would the magnetic field penetrate inside the hollow sphere? If not I have created a magnetic shield!

"flux pinning would slow the SC down pretty quickly." Where can I find experimental results regarding such behaviour? Is it reported anywhere? Is there a plain english explaination regarding this? My hunch is that the superconductor will not slow down because of the absence of electromagnetic drag force?

If a magnet is brought near a rotating copper disc, the disc will slow down. This is because of the electromagnetic drag force. Does the same thing happens to a rotating superconductor disc?

Let's say I have a hollow sphere covered with a superconducting material immersed in liquid nitrogen. If a weak magnet is brought near it would the magnetic field penetrate inside the hollow sphere? If not I have created a magnetic shield!

If a magnet is brought near a rotating copper disc, the disc will slow down. This is because of the electromagnetic drag force. Does the same thing happens to a rotating superconductor disc?

"Yes, copper is often used for heat-sinking, thanks to its excellent thermal conductivity and not terrible heat capacity" Is heat capacity more useful as a heat sink then heat conductivity? If heat conductivity is high the heat will immediately be dissipated elsewhere in the equipment. On the other hand if heat capacity is high it will absorb more heat.

I thought copper is normally used as a heat sink?

I have done some calculations using the empirical result from the website. I generally got this type of equation: F = ax^2 + bx + c where F=Force between identical magnets & x=separation distance between identical magnets. It can be inferred that for small separation distances F=bx + c and large separation distances F=ax^2. Is this above reasoning logical. It is based on empirical evidence. Should it be F=ax^4 + bx^3 + cx^2 + dx + e ?

"The force needed to push the two magnets together is easy. F=2 pi M^2 A, where M is the strength of each magnet in gauss, and A is the cross-sectional area of the tube." The force DOES depend on the product of the two fields!