How can the neutral outer core generate a magnetic field?

In summary: I wonder if they actually measured the field Strength.In summary, according to recent work, a magnetic field may spontaneously develop in a liquid when the volume is large enough.
  • #1
AustinLee
7
0
Even if the outer core is convecting and conductive it is still charge neutral, so how can a Magnetic field be generated? Maxwells Equation say there needs to be net charge moving for a Magnetic field to be generated.
 
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  • #3
I assume we're talking about Earth's core?
 
  • #4
AustinLee said:
Even if the outer core is convecting and conductive it is still charge neutral, so how can a Magnetic field be generated?
A current-carrying wire is charge-neutral, nevertheless it generates a magnetic field. Its negative charges (mobile electrons) move, but the equal amount of positive charge (metallic ions) does not.
 
  • #5
jtbell said:
A current-carrying wire is charge-neutral, nevertheless it generates a magnetic field. Its negative charges (mobile electrons) move, but the equal amount of positive charge (metallic ions) does not.
Okay I can understand the neutrality. However does that mean the Earth's outer core has a electrical current?
 
  • #7
AustinLee said:
Even if the outer core is convecting and conductive it is still charge neutral, so how can a Magnetic field be generated? Maxwells Equation say there needs to be net charge moving for a Magnetic field to be generated.
So let's assume there is a magnetic field (maybe much weaker than the magnetic field of earth) and a neutral conductive liquid is moving in this field. Then there will be some charge separation as the electrons and nuclear charges are deflected in different directions. The amount of charge built up will be limited by the build up of an electric field till some equilibrium is reached. Nevertheless the speed of negative and positive charges may be different thus leading to an additional magnetic field. If oriented parallel to the original field, this can lead to a rapid build up of a strong magentic field starting from a small random field fluctuation.
 
  • #8
Wasn't there recent work using a stirred, near-spherical tank of liquid Sodium ?? If the volume was big enough, a bipolar magnetic field spontaneously developed...
I find that astonishing...
 

1. How does the neutral outer core generate a magnetic field?

The outer core generates a magnetic field through a process called convection. This is the movement of molten iron and nickel within the outer core due to the extreme heat and pressure. As the liquid metal moves, it creates electric currents, which in turn generate a magnetic field.

2. What causes the neutral outer core to generate a magnetic field?

The main cause of the neutral outer core generating a magnetic field is the rotation of the Earth. This rotation causes the liquid metal in the outer core to move in a circular pattern, creating electric currents and therefore a magnetic field.

3. Can the neutral outer core's magnetic field change over time?

Yes, the neutral outer core's magnetic field can change over time. This is due to the constant movement of the liquid metal in the outer core, which can cause fluctuations in the strength and direction of the magnetic field.

4. How does the neutral outer core's magnetic field protect the Earth?

The neutral outer core's magnetic field acts as a shield, protecting the Earth from harmful solar radiation and charged particles from the sun. These particles are deflected by the magnetic field, preventing them from reaching the Earth's surface.

5. Is the neutral outer core's magnetic field important for life on Earth?

Yes, the neutral outer core's magnetic field is crucial for life on Earth. Without this magnetic field, the Earth's atmosphere would be eroded by the sun's radiation, making it impossible for life to exist. Additionally, the magnetic field also plays a role in navigation, as it helps animals and humans to navigate using the Earth's magnetic field.

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