How do liquid planets generate a magnetic field?

AI Thread Summary
Liquid planets generate magnetic fields due to their ability to conduct electric currents, facilitated by differential rotation. In contrast, solid planets do not produce magnetic fields because they act as insulators and lack the necessary fluid dynamics. To create a planetary-scale magnetic field, a net electric current is essential. The geodynamo and dynamo theory explain the complex physical processes behind this phenomenon. Understanding these concepts clarifies why only partially liquid planets can generate magnetic fields.
ImaLooser
Messages
486
Reaction score
4
So solid planets do not generate a magnetic field. Planets that are at least partially liquid do because they have differential rotation. I don't understand this, there is some basic concept that I'm missing. I don't even know what question to ask.
 
Physics news on Phys.org
To get a magnetic field on the scale of a planet you need a net electric current.
The physical process is quite complicated...
http://en.wikipedia.org/wiki/Earth's_magnetic_field#Physical_origin
... look up "geodynamo" and "dynamo theory".
http://en.wikipedia.org/wiki/Geodynamo

Oversimplified - the fluid arts can carry an electric current while the solid planets are insulators right through. For a solid planet's rotation to give you a magnetic field there has to be an uneven charge distribution through the planet.
 

Thread 'Maxwell stress tensor'

This is from Griffiths' Electrodynamics, 3rd edition, page 352. I am trying to calculate the divergence of the Maxwell stress tensor. The tensor is given as ##T_{ij} =\epsilon_0 (E_iE_j-\frac 1 2 \delta_{ij} E^2)+\frac 1 {\mu_0}(B_iB_j-\frac 1 2 \delta_{ij} B^2)##. To make things easier, I just want to focus on the part with the electrical field, i.e. I want to find the divergence of ##E_{ij}=E_iE_j-\frac 1 2 \delta_{ij}E^2##. In matrix form, this tensor should look like this...
View full post »
Thread 'Applying the Gauss (1835) formula for force between 2 parallel DC currents'

Thread 'Applying the Gauss (1835) formula for force between 2 parallel DC currents'

Please can anyone either:- (1) point me to a derivation of the perpendicular force (Fy) between two very long parallel wires carrying steady currents utilising the formula of Gauss for the force F along the line r between 2 charges? Or alternatively (2) point out where I have gone wrong in my method? I am having problems with calculating the direction and magnitude of the force as expected from modern (Biot-Savart-Maxwell-Lorentz) formula. Here is my method and results so far:- This...
View full post »

Similar threads

I Charge movement relative to magnetic field frame dependence/invariance
Replies
5
Views
919
I Origin of the Earth's magnetic field
Replies
8
Views
2K
B Magnetic field and generator power output
Replies
5
Views
2K
I Motional EMF in Faraday disc, co-rotating magnet axial mean flux
Replies
5
Views
157
How closely do the magnetic fields generated by geodynamos align?
Replies
2
Views
921
I Induced electric fields and induced magnetic fields confusion
Replies
9
Views
3K
I Homopolar generator question: Magnetic “wake”
Replies
7
Views
3K
I Behaviour of Magnetic Fields Underwater
Replies
2
Views
3K
I Magnetic dipole and a torque
Replies
1
Views
671
I Geometry of Magnetic field lines as they approach a magnet pole?
Replies
28
Views
3K

Hot Threads

Recent Insights

Back
Top