Electrostatic magnetic-field interaction

AI Thread Summary
The discussion centers on the interaction between electrostatic charges and magnetic fields, particularly in the context of a negatively charged van de Graaff generator. It highlights that static magnetic fields do not affect static charges, as the Lorentz force only acts on moving charges. However, moving a magnet can induce eddy currents in conductive materials, which may influence the behavior of charges. Rapid changes in magnetic fields can induce voltages that affect static electric charges, but charges on insulators are bound by electrostatic potential, making them difficult to displace. The conversation concludes with a query about methods to temporarily introduce extra electrons into a conductor using electrostatic charging combined with pulsed electromagnetic fields.
ace333
Messages
7
Reaction score
0
simple eg: negatively charged van de graaff generator top and a magnet. Put magnet near top. Would the magnetic field push the electrons of the charged surface to the sides and deeper into the metallic top?
 
Physics news on Phys.org
A charged van de graaff generator is very nearly in equilibrium: it has very little current. Why would the magnet push the electrons in any way?
 
I'm referring to the localised area within a few millimetres from the magnet.
 
Magnets have no effect on static charges, but slowly moving electrons curl up in a magnetic field. In a crossed electrostatic magnetic electric field, the electrons move in a cycloidic manner.
Bob S
 
Why is there no effect on static charges since the electrons are the same
free electrons as in a conductor and on those there is of curse such a
strong effect induced on the same free electrons by a magnetic field. What is the difference since the conductors free electrons are just as static as the electrostatic charge and it is only their abundance that is different. So why can’t they be moved by a magnetic field?
 
ace333 said:
Why is there no effect on static charges since the electrons are the same
free electrons as in a conductor and on those there is of curse such a
strong effect induced on the same free electrons by a magnetic field. What is the difference since the conductors free electrons are just as static as the electrostatic charge and it is only their abundance that is different. So why can’t they be moved by a magnetic field?
The only force on a charge by a static magnetic field is when the charge is moving. It is given by the Loeentz force F:

F = q(E + v x B), where the 2nd term is the vector cross product.

The magnet can prevent slow electrons from moving toward (and "sticking to" for dielectric surfaces) surfaces near the magnet poles.
Bob S
 
"The only force on a charge by a static magnetic field is when the charge is moving."

So since movement is relative than as a magnet is being moved towards (or away) from the metallic negatively charged van de graaff top than the electrostaticly accumulated electrons could be effected, no?
 
Good questions. When a magnet is moved toward or away from a metallic surface, eddy currents are induced in the metallic surface that slow down and retard the dB/dt (changes) in the magnetic field perpendicular to the metallic surface. However, changes in magnetic fields (dB/dt) parallel to the metallic surfaces (if non-magnetic) are only slightly affected. A rapid change in magnetic fields (dB/dt) can induce voltages (Faraday's Law) that will affect static electric charges. But the electric charges on insulators are bound to the insulator by an electrostatic potential called a work function that requires large local electric fields to remove. So even a large dB/dt is not likely to pull charges away from insulators. "Electrostatic" charges on metallic surfaces are image charges due to opposite sign charges either in space (space charge, including ion or electron beams) or on insulating surfaces elsewhere. These charges are unlikely to move.
Bob S
 
Last edited:
THANK YOU> SO Is there a way to mix extra electrons (a non permanent net gain during exposure time) deep into a conductor momentarily without biologically damaging methods? Like electrostatic charging and discharging i.e. moving charges, coupled with rapid pulsed electromagnetic fields? Would the moving charges (high voltage electrostatic) be affected by the changing magnetic fields enough to move off the surface deeper into the conductor momentarily?
 

Similar threads

Back
Top