# Tag Info

122

Earth has a magnetic field. You can verify this yourself; it is why a compass works. Just take any magnet and hang it carefully from a string. As long as there's nothing else magnetic around and it's well-balanced and free to rotate, it will line up with Earth's magnetic field. We have measured the Earth's magnetic field all over the surface and up into ...

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Not really. A magnetic field alone doesn't create electricity. A changing magnetic field does. The Earth's magnetic field does change a tiny bit but not enough to really generate much. The other option is to move the inductor in the magnetic field. The Earth's magnetic field is quite homogeneous over short distances though so the coil would need to move ...

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The lift generated by magnetic field B on a superconductor of area S is: $$F = \frac{B^2S}{2\mu_0}$$ disregarding lateral forces and assuming superconducting cylinder (or similar shape) with area S at the top and bottom and height h, we need three forces to remain in the equilibrium: magnetic pressure on top, bottom and gravity ...

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short answer : no , there is a random cycle versus the very regular astronomic cycle of the assumption. Magnetic field reversals Evidence for these geomagnetic reversals can be found worldwide in basalts, sediment cores taken from the ocean floors, and seafloor magnetic anomalies. Reversals occur at apparently random intervals ranging from less ...

5

Yes, Earth does have a magnetic field(check it out with a compass!). In geology, they explain this in this way: The Earth's core is divided between the inner and outer cores. The inner core is solid because of the very high pressure. The outer core, although it also has high pressure, it is not as high as the inner core and thus it is not solid, but fluid. ...

5

Yes, the geomagnetic field does rotate with the earth. This is the reason why maps of the geomagnetic field overlaying geographic coordinates are reasonably accurate for a decade or two - and why a compass is still useful for navigation. (i.e. You do not need to know the time of day in order to correct for the magnetic declination cited on your map!) The ...

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Yes, the Earth's magnetic field does rotate with the Earth. There is a simple way and a complicated way to explain this. Firstly the simple way: the magnetic north pole and the North Pole are not at the same point. That means if the magnetic field did not rotate with the Earth the magnetic north pole would rotate once around the North pole every 24 hours. ...

4

Circulating neutral particles will not by themselves create a magnetic field. However, if the neutral particles are moving through an existing magnetic field, and the neutral medium is conducting, then the magnetic field will induce a current via the Lorentz force. That induced current will in turn create it's own magnetic field, which may enhance the ...

3

You can't generate power from a static magnetic field alone. In this context, the earth is just a permanent magnet, and a rather weak one at that. To generate electric power from that, you have to move electric conductors, like wires, thru the field in the right direction and with the right orientation of the conductor. If any electric power is taken from ...

3

The Earth's magnetic field is caused by eddy currents in the liquid parts of the planet's interior. We believe the field is not due to a permanent magnet because: (1) Its direction and strength change over time, and (2) the planet's interior is hotter than the Curie temperature of its elements, and so a permanent magnet would not retain its magnetism. ...

3

The north-seeking pole always points toward magnetic north, assuming it is only feeling Earth's magnetic field. A magnet has no idea (so to speak) which direction is geographic north. Any source that tells you that a magnet points geographically north is only as correct as the statement that geographic north and magnetic north are the same direction.

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Magnetic surveys are used for prospecting for oil or minerals. On top of the earth's magnetic field there are small contributions form magnetic materials in the surface rocks, especially granites. You can use this to either find large bodies of volcanic rock that migth have minerals or diamonds - or alternatively you can find large volumes with no magnetic ...

3

Multiple sheets of steel work nicely to attenuate magnetic fields with higher frequencies but they are not great if you want to shield against small and constant fields. To shield the earth's magnetic field the best material has a high permeability with almost zero hysteresis. There are some metallic glasses, such as Ultraperm, Vitrovac or Metglas that I ...

3

The physical explanation for the origin of the geomagnetic field is that it is caused primarily by electric currents (moving charge) in the Earth's liquid outer core. The composition of the outer core is thought to be largely iron. The temperature in the core is above the Curie temperature of iron, which means the magnetic field of the core is not caused by ...

3

The mechanisms of pole reversal are not fully understood, but current theory is supported well by mathematical simulations. The primary structure understood to be responsible for advection, the generation of the Earth's magnetic field, is the outer core, a fluid layer comprised primarily of iron and nickel which lies between (roughly) 2900 to 5200 ...

2

Here is the home page for the GUFM model website. It also includes a link to a freely available pdf of the modern reference. Also of interest is the NOAA WEBSITE. GUFM MODEL HOMEPAGE NOAA PAGE Note that this model is based upon catalogs of geomagnetic field measurements, these did exist prior to 1800 - although as you would expect their quality and ...

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Apologies for the hasty questioning. I found the reference in the File Description of the wikipedia image description page. The model is apparently called the GUFM model, for which a good reference is Four centuries of geomagnetic secular variation from historical records. A Jackson, A R T Jonkers and M R Walker. Phil. Trans. R. Soc. Lond. A 358 no. 1768 ...

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You don't need a separated electric charge for the Earth's core to generate a magnetic field, and you don't even need a ferromagnet. This experiment simulates the magnetic field generation by using a model of the core containing liquid sodium. Actually I'm not sure if they've got it to work yet, so maybe I should say may simulate rather than simulates. You ...

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The magnetic axis of the Earth is defined as the axis of the closest fitting magnetic dipole to Earth's magnetic field. The magnetic field of the Earth is not exactly a dipole, it is even asymmetric between the Northern hemisphere and the southern hemisphere: the North magnetic pole is located at 86.27°N and the South magnetic pole at 64.26°S. Moreover, ...

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A magnet (including an electromagnet) in a uniform magnetic field feels a torque (twist) but no net linear force (thrust). It is only when the external field varies (in magnitude and/or direction) that when you average over an entire magnet you get an unbalanced linear force. When you have two magnets in your hand, you can feel them pushing, pulling, ...

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You ask a lot of questions, I'll try to answer just one. As the Earth's magnetic field protects us from ionizing radiation, theoretically, there can be negative correlation between the Earth's magnetic field and cancer incidence. EDIT: see, e.g., Health Physics; v. 34(3) p. 237-247; ISSN 0017-9078; 1978 (https://inis.iaea.org/search/search.aspx?orig_q=RN:...

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This particular orientation sensing protocol is not wonted to me, but the following, given the data you cite, will indeed give you your orientation in space: Magnetometer gives $\vec{N}_0$ north direction (in general, not parallel to the "ground" because it has magnetic dip included); Gravity accelerometer gives $\vec{D}$ "down" direction; Then $\vec{D}\... 1 What is the origin of the geomagnetic field? The Earth's magnetic field can't be a permanent bar magnet. Permanent bar magnets aren't that permanent. A bar magnet would only last a few tens of thousands of years before it decayed. That's extremely short in geological terms. The Earth's magnetic field has been around for billions of years. Something has to ... 1 I write this because it is too long for a comment Situation You are putting$k$watts (=joules/second) of kinetic energy into a body. We will show the acceleration decreases with time. $$E=\frac{1}{2}mv^2$$ so $$v=\sqrt{\frac{2E}{m}}$$ so $$\frac{dv}{dt}=\frac{m}{\sqrt{\frac{2E}m}}\cdot\frac{de}{dt}$$ (I can't be bothered to tidy this up - remember I'm ... 1 The Earth rotates around an axis. Denote the unit vector directed along this axis (with the direction determined by the right hand rule) as$\hat z\$. This rotational axis is key in finding "north". I'll assume a nice simple geometrically shaped Earth, either a sphere or an ellipsoid, and I'll assume a person who is not standing on the north or south pole. ...

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Simply: if the line from your position to the magnetic North also goes through the geographic North, your magnetic declination will be zero. This happens at every point along the great circle that includes magnetic North and the North Pole. Note that in reality there are sufficient iron ore deposits in the earth to disturb the "ideal" picture above - see ...

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Also if a compass aligns in the direction of horizontal component of MF at that place does this mean that at any place horizontal component is directed towards the magnetic north ?? That's exactly what it means. That's the definition of magnetic north. If u look at a bar magnet's field lines not every tangent to the curve will pass through the north pole. ...

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Because the magnetic field does not align with the geographic axis, most places will show a variation between true north and magnetic north. However since some areas have an east variation and some areas have a west variation, there must be a border between those areas where the variation just happens to be zero.

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You might be able to figure this out by looking at the following picture (source: http://www.unc.edu/depts/oceanweb/turtles/geomag.gif): As you can see, the field lines point into the earth.

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