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What is Magnetic Field Strength?

Jupiter's magnetic field is 1/3,000th of a tesla, which is ten times stronger than Earth's magnetic field.
The magnetic field strength on earth keeps a compass pointing north.
An electromagnet. Magnetic field strength is measured in teslas.
A magnetic field of 17 teslas can levitate a frog.
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  • Written By: Michael Anissimov
  • Edited By: Bronwyn Harris
  • Last Modified Date: 24 November 2014
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Magnetic field strength is a measure of the intensity of a magnetic field, given in teslas (T), the standard unit. One tesla is equal to one weber per square meter, where one weber is the equivalent per second that is required to induce an electromotive force of one volt. Another way to define a tesla is that a magnetic field of 1 tesla must exert force of 1 newton on a wire of 1 meter carrying 1 ampere of current. This is a lot of force for a magnetic field to exert, as a newton is the force necessary to accelerate a 1 kg weight at 1 meter per second squared.

If all that sounds complicated, people can just think of magnetic field strength in teslas by reference to known field strengths. For instance, the Earth's magnetic field is equivalent to 1/30,000th of a tesla. Still, this is enough for birds to navigate by and to keep a compass hand pointed north. The magnetic field of Jupiter, the largest planet in the solar system, is about ten times stronger than Earth's, or 1/3,000th of a tesla. This is caused by charge circulating through metallic hydrogen in its interior.

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Though the magnetic field strength of planets is relatively small, much stronger magnetic fields can be generated through artificial means. A typical loudspeaker magnetic generates a strength of 1 to 2.4 teslas. The magnetic field necessary to levitate a frog is about 17 teslas. The strongest electromagnets, which make use of superconductors, measure approximately 20 teslas. The strongest continuous magnetic field yet generated is 45 teslas, at Florida State University's National High Magnetic Field Laboratory in Tallahassee, while the strongest pulsed magnetic field obtained non-destructively was 100 teslas at the Los Alamos National Laboratory. By generating a magnetic field with an explosively pumped flux compression generator, researchers have been able to achieve a short-lived magnetic field of 2,800 teslas.

The Earth's magnetic field is equivalent to 1/30,000th of a tesla.
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NathanG
Post 4

When I played with electronics kits as a kid, one of the first experiments I performed was with magnets and electricity.

I wrapped a metal tube with wire and moved a magnet back and forth inside the tube. The result was magnetic induction. I connected the wires to a meter and could see the needle moving back and forth to indicate the presence of an electric force.

Charred
Post 3

@Qohe1et - Given what we know about the strength of a magnetic field, perhaps it would be possible to build an anti gravity device someday. Right now anti gravity is relegated to the domain of fringe or junk science.

I realize there are people on the Internet who claim to have already built such a device, but I don’t pay much attention to them.

If they had truly built an anti gravity machine, they would be accepted by the scientific community and their work would be published in journals. Most of these guys act like they’re outcasts who are being shunned because their work threatens the Big Energy establishment.

Anyway, I still believe in principle we can marshal magnetic field strength energy to build such a device. The problem right now is that of magnetic field strength vs distance. That is, the further away you get from a field, the less force it exerts.

Qohe1et
Post 2

@hangugeo112

I don't know if this is quite possible. An electromagnetic field generator would be immensely dangerous if it were possible to construct. We could disrupt the earth's orbit. It also would be vastly beyond our capability to construct something which would stop or reverse the incredibly powerful trajectory of a meteor. Some meteors are so massive and fast that they could obliterate us completely.

hangugeo112
Post 1

It is to be hoped that we will someday have technology in electromagnetic force which is strong enough to repel meteorites and keep them far from the earth's atmosphere.

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