Magnetic field strength of the earth in center

[gre]

Does the strength of earth's magnetic field increase towards the center/core?

[thedarkshade]

Does the strength of earth's magnetic field increase towards the center/core?

I assume so, but toward the poles of the center.

[Klaynos]

I don't know. But you'd have to take into account that the magnetic field is NOT coming from a point source, there would be some strength gradient that will probably increase as you go threw the crust (as little of the field comes from the crust I'd imagine) and then at some point it'd start dropping off again, as you go "inside" the most magnetic regions...

[npts2020]

I have nothing to back this up but I would think the strongest field would either be at the edge of where the core becomes molten or halfway from there to the center, not in the exact center. Where is the strongest field in a bar magnet? If the core is what causes our magnetosphere could it not be modelled like a spherical bar magnet?

[gre]

Well how could you calculate the magnetic field strength near the center of the earth? Is it possible?

[Klaynos]

I have nothing to back this up but I would think the strongest field would either be at the edge of where the core becomes molten or halfway from there to the center, not in the exact center. Where is the strongest field in a bar magnet? If the core is what causes our magnetosphere could it not be modelled like a spherical bar magnet?

 

The strong field in a bar magnet is at the poles, I believe this holds for the earth. The magnetosphere is not caused by the same mechanisim, it's electric currents in the upper atmosphere, whereas the earths field is from electric currents in the outer molten core.

 

A better model might be a current loop...

 

Well how could you calculate the magnetic field strength near the center of the earth? Is it possible?

 

I honestly don't know, you could measure the current at the surface and assume there's nothing big happening on average in between the surface and the molten core but I can't think of a more direct measurement technique.

[gre]

Could you do something like this?

 

 

(4*pi*earth_radius^2) * magnetic_field_strength_earths_surface

5.10352e14 m^2 * 3e-5 T = 1.53e10

 

Then use this number to scale down?

[Klaynos]

As you've multiplied by the surface of the earth, that number will be the same close to core, (being the total field) the field/unit area is just that /the area of the sphere you're considering. So yes it's just scaled.

[gre]

So, why can't you say the magnetic strength at the center of the earth in a spherical-meter is 1.53e10 T?

[D H]

Could you do something like this?

 

 

(4*pi*earth_radius^2) * magnetic_field_strength_earths_surface

5.10352e14 m^2 * 3e-5 T = 1.53e10

 

Then use this number to scale down?

No. You can't just make up a formula and expect it to be valid.

 

You are implicitly assuming that the Earth's magnetic field strength varies with the square or inverse square of the radial distance. Not sure which you are implying here; you don't even have an equation (i.e., something of the form y=f(x)).

 

What makes you think this would be valid? (Hint: It isn't). To zeroth order, the Earth's magnetic field intensity beyond the Earth's surface is proportional to the inverse cube of radius. Moreover, the Earth's magnetic field away from the Earth's surface has a lot of high-order moments. To get a picture of what goes on inside the Earth you will need to study magnetohydrodynamics.

[Klaynos]

You've got the wrong units there, you've got the total field strength value, but with the units of field per square metre.

[gre]

No. You can't just make up a formula and expect it to be valid.

 

You are implicitly assuming that the Earth's magnetic field strength varies with the square or inverse square of the radial distance. Not sure which you are implying here; you don't even have an equation (i.e., something of the form y=f(x)).

 

What makes you think this would be valid? (Hint: It isn't). To zeroth order, the Earth's magnetic field intensity beyond the Earth's surface is proportional to the inverse cube of radius. Moreover, the Earth's magnetic field away from the Earth's surface has a lot of high-order moments. To get a picture of what goes on inside the Earth you will need to study magnetohydrodynamics.

 

 

So, in other words, you have no idea how to calculate the magnetic field strength in the center of the earth. Give it a shot. What do you think the formula would be?

 

btw, I didn't expect my formula would be valid.

Edited December 23, 2008 by gre