Could someone please explain, in layman's terms, how electro-magnetism works? Doesn't it have something to do with the magnetic poles of the earth? I recently attended a Science Fair at my daughter's school and one of the projects there was an electro-magnet. I found it to be interesting. Someone had wrapped a nail with wire, then attached both ends of the wire to the terminals of a battery, thus creating a basic electro-magnet. I wondered is it possible to create the reverse effect? Like when you try to put the positive end of a magnet against another positive end of a magnet, they repel. Could that effect be produced with an electrical charge, same as the electro-magnet, only with the opposite effect?
Could not this idea have the potential for practical application? For instance, could it be applied to the concept of "hover conversions" of vehicles? Creating an electro-magnetic charge beneath a vehicle strong enough to keep it suspended in the air? If possible, could this application ever hope to be stable enough to move while "hovering"? On a lesser scale, this could maybe be applied to skateboards, i.e. "hoverboards".
Sounds like science fiction, I know. But, I'm sure the concept of cars and jets sounded the same way when they were first dreamt up.
Originally posted by Valor D: Could not this idea have the potential for practical application? For instance, could it be applied to the concept of "hover conversions" of vehicles? Creating an electro-magnetic charge beneath a vehicle strong enough to keep it suspended in the air?.
Sounds like science fiction, I know. But, I'm sure the concept of cars and jets sounded the same way when they were first dreamt up.
First off, there's an issue with terminology. An electromagnet (no hyphen) is what you saw demonstrated at the science fair, Valor D. Electromagnetism is usually used in a broader sense to encompass all phenomena related to electricity and magnetism. It sounds like you're mainly asking about electomagnets.
Brief historical digression: Electricity and magnetism were considered separate phenomena until peculiar connections between them were discovered, as illustrated by an iron bar magnetized by an electrical current encircling it. Eventually they were combined into a unified theory of electromagnetism and enshrined in the near-symmetrical Maxwell's Equations. After Einstein ironed out a few kinks, and with a few other equations thrown in, the theory was pretty much done (though the future discovery of magnetic monopoles might require another patch).
So in the electromagnet, as current flows through a wire it generates a magnetic field surrounding the wire. When you form the wire into a circular loop, the magnetic field ends up pointing perpendicular to the loop. Making multiple turns of the coil strengthens the effect. Putting a ferromagnetic core, such as an iron nail, inside the coil further strengthens the effect.
Valor, you asked about "creating the reverse effect" of the electromagnet. Yes, here's what you could do: Remove the power source and replace it with an ammeter to measure current or a voltmeter to measure voltage. At rest the meter reads zero. Now take a nail-sized permanent magnet (use the original nail, if it's already magnetized) and slide it in and out of the coil. A current and voltage will be induced and vary as you move the magnet, first shown by Faraday in the 1830s. Application of this principle is the basis for many power generators.
These reciprocal relationships -- symmetries -- are what led Maxwell to his nice set of four equations that synthesize the results of so many kinds of experiments into one consistent set of principles. It was Maxwell's equations that predicted radio waves, later discovered by Hertz.
They require advanced math, however, because they must take into account how the fields are changing with time.
But Valor, you're asking about repulsion rather than attraction. Here again, electricity and magnetism have a similar relationship: Unlikes attract and likes repel. This rule applies to positive and negative electrical charges, and it applies to north and south magnetic poles.
Despite the cool hoverboards seen in the Back To The Future series, there is something called Earnshaw's theorem that
quote:
...proved conclusively that it is not possible to stably levitate using only static, macroscopic, "classical" electromagnetic fields. The forces acting on an object in any combination of gravitational, electrostatic, and magnetostatic fields will make the object's position unstable. However, several possibilities exist to make levitation viable, by violating the assumptions of the theorem — for example, the use of electronic stabilization or diamagnetic materials.
In other words, if you want to levitate, there has to be some kind of mechanism to provide stability, which requires adding energy to the system.
This is where FredPuli's maglev trains enter the scene. They can be quite efficient owing to zero rolling friction, there being no physical contact between train and rail. But they still require power to levitate, not to mention additional power for forward propulsion against air resistance.
A hoverboard or similar system IS possible, on second thought. I would envision it as a software-driven networked mesh of field generators and sensors to levitate and push people along without colliding. This would require the installation of infrastructure on a massive scale.
I'd add that there's also a form of magnetic levitation known as the Meissner effect, involving superconductors (not your everyday materials!):
quote:
A magnet that is suspended by the superconductor has two interesting properties; it does not move, and it can spin without friction. The ability for the magnet to stay perfectly still is due to flux pinning, in which the magnetic field lines become trapped within the superconductor at sites of impurity in the crystal structure.
Hope this answers your questions.
Posts: 2067 | Location: U.S. | Registered: 06-03-02
Ok, so it sounds like the only presently known way to make it work would be to have another magnetic surface beneath it, or surrounding it, and even then, it wouldn't be stable.
But, isn't the earth itself essentially a magnetic pole? Doesn't the ground itself contain a (negative) magnetic charge? Could not this be used as the secondary magnetic surface?
Sorry if my terminology isn't up to par with you physics majors. I'm just a curious guy with some some ideas, but lacking in the formal scientific education to put them into motion.
My initial question was "how does electromagnetism work"? I'de still like to know.
My initial question was "how does electromagnetism work"? I'de still like to know.
If a conductor (such as a copper wire) and a magnet are situated in close proximity to each other, such that the conductor is within the magnet's field of force,If either one or the other moves, or if there is relative motion between them, an electric current is generated.in the wire.
This is the principle of how an electric current is generated. Wires, wound on an armature of some sort, are caused to rotate within a magnetic field. The magnetic field can be either a permanent magnet, as in the old-fashioned magneto that used to be cranked to ring a 'phone, or a bicycle generator rotated by friction against the wheel of the bike.
The motion required to generate electricity can be relative, one, either or both can move, or (in the case of transformers) one current carrying wire, energized by an alternating electric current, provides a "moving" magnetic field. This pulsating or "moving" field causes the movement of electrons in the other winding, ergo: a flow of electrons=an electric current.
I know this is getting longer and more difficult to explain in one short post, and it's getting past my bedtime. If professor or someone else doesn't do this better, I'll be back and find some link, with illustration, etc.
The planets travel without friction in the vacuum. This means the vacuum is an empty space. Light waves are transverse waves, therefore it means the vacuum must be as firm as steel. How does a quantum of light move in such an unintelligible vacuum? -------------------- The common answer is that light consists actually of two waves, an electric wave and a magnetic wave. According to Maxwell's equations, both induce and thus maintain each other mutually, and thus there is no need for a medium and the light can propagate in a vacuum. ------------------------ I studied this concept 50 years ago, but ...50 years have passed... And now I cannot take the school concept seriously. Why? Because: 1. I think it is impossible that electric and magnetic waves exist at the same time. Between them, there must be a very short rupture of time. Then at some moment light will be an electrical wave, and in another moment, a magnetic wave. But this electrical waves must be a transverse wave, which means that the vacuum is as firm as steel. Unless am I wrong? 2. It is 100% right that " an electric wave and a magnetic wave, according to Maxwell's equations, both induce and thus maintain each other mutually". But this statement is right only according to classic ( macro) electrodynamics. When Maxwell's electrodynamics is used in the microworld, then it requires the idea of "quantum of light".
3. It is not correct to use the common word "light" in quantum theory. The word "light" is possible to use on a beach, in a market, in every another place, but not in quantum theory. Here it is necessary to say "quantum of light". 4. And now everybody knows that light quanta is a wave and particle at the same time. And when somebody says : "that light consists actually of two waves, an electric wave and a magnetic wave", he forgets the photon is a particle also. The usage of only wave abilities is not enough to explain the photon’s motion The picture of the photon's action is not complete. Then....... If we want to see the whole picture of photon’s motion, we must imagine that its motion jumps from an electric wave to a magnetic wave and back, from a magnetic wave to an electric wave and back, and back........ I see my explanation is difficult. Maybe it is better and simpler to imagine the photon driving a bicycle when one wheel is an electric wave and another wheel is a magnetic wave. But this bicycle is very strange: one wheel ( an electric wave ) must be perpendicular to another wheel (a magnetic wave). Sorry. I only want to say that to use sentences like, "light quanta is wave and particle at the same time", "light consists actually of two waves - an electric wave and a magnetic wave in its motion in a vacuum" is not correct. An electromagnetic field is thought to be made up of photons and waves which are interchangeable. P.S. Imitating some methodology:
There are birds that can walk, fly and swim. The birds who don’t have one of these abilities are not birds. /according to complementarity and the Copenhagen interpretation of quantum mechanics, of course./ ==========.. http://www.PlanetBozo.com
This message has been edited. Last edited by: DorianGreyed,
Posts: 127 | Location: israel | Registered: 12-05-05
Apparantly, this guy has managed to invent some flying cars without the complexities of electromags. It seems he prefers the use of jet engines. Although his latest creation looks more like something George Jetson drives/flies: http://www.msnbc.msn.com/id/20535980/?GT1=10357
