Question about spherical capacitor and magnetic fields

[Bkas]

Is there a magnetic field induced by a solid charged sphere surrounded by a spherical shell (oppositely charged) with a very weak conducting dialectric inserted in between (current going outward, from solid sphere to outer shell). Would it still induce a magnetic field? I can't picture what direction it would go...I think it violate's a Maxwell equation, but I'm not sure.

Any thoughts?

 

[Joemonkey]

Try posting that in the Highly Technical section of the forum

 

[deftron]

Here you go, Einstein

 

[theNEOone]

this isn't a "highly techinical quesiton"

2nd semester physics guys....common

 

[theNEOone]

btw, the answer is pretty easy. a magnetic field is only induced by moving charges. no moving charges in your description, so no magnetic filed.

 

[dighn]

Originally posted by: theNEOone
btw, the answer is pretty easy. a magnetic field is only induced by moving charges. no moving charges in your description, so no magnetic filed.

u should read the post a little more carefully

not only did he say there is a weakly conducting dielectric material which implies a current, there is also a changing electrical field due to the discharging, which induces a magnetic field

anyway just a guess but the currrent & the changing e field might geberate cancelling b field. this is just at a glance so .. i got an exam on this stuff in about a week so i might take a bette rlook at this later tonight

 

[Bkas]

Originally posted by: dighn

Originally posted by: theNEOone
btw, the answer is pretty easy. a magnetic field is only induced by moving charges. no moving charges in your description, so no magnetic filed.

u should read the post a little more carefully

not only did he say there is a weakly conducting dielectric material which implies a current, there is also a changing electrical field due to the discharging, which induces a magnetic field

anyway just a guess but the currrent & the changing e field might geberate cancelling b field. this is just at a glance so .. i got an exam on this stuff in about a week so i might take a bette rlook at this later tonight

Yeah, i've got an exam coming up this week as well. So if you figure it out, let me know.

How is it a time changing e-field due to dicharging? there's isn't an e-field outside the spherical capcacitor...

 

[dighn]

Originally posted by: Bkas

Originally posted by: dighn

Originally posted by: theNEOone
btw, the answer is pretty easy. a magnetic field is only induced by moving charges. no moving charges in your description, so no magnetic filed.

u should read the post a little more carefully

not only did he say there is a weakly conducting dielectric material which implies a current, there is also a changing electrical field due to the discharging, which induces a magnetic field

anyway just a guess but the currrent & the changing e field might geberate cancelling b field. this is just at a glance so .. i got an exam on this stuff in about a week so i might take a bette rlook at this later tonight

How is it a time changing e-field due to dicharging? there's isn't an e-field outside the spherical capcacitor...

i thought you meant between the sphere and shell.

but outside i'm nto sure. amphere's law should still apply..

 

[theNEOone]

Originally posted by: dighn

Originally posted by: theNEOone
btw, the answer is pretty easy. a magnetic field is only induced by moving charges. no moving charges in your description, so no magnetic filed.

u should read the post a little more carefully

not only did he say there is a weakly conducting dielectric material which implies a current, there is also a changing electrical field due to the discharging, which induces a magnetic field

anyway just a guess but the currrent & the changing e field might geberate cancelling b field. this is just at a glance so .. i got an exam on this stuff in about a week so i might take a bette rlook at this later tonight

i should have read a little closer, but a "weakly conducting dielectric material" DOES NOT imply a current whatsoever. paper is a "weakly conducting dielectric material."

 

[Bkas]

Originally posted by: theNEOone

Originally posted by: dighn

Originally posted by: theNEOone
btw, the answer is pretty easy. a magnetic field is only induced by moving charges. no moving charges in your description, so no magnetic filed.

u should read the post a little more carefully

not only did he say there is a weakly conducting dielectric material which implies a current, there is also a changing electrical field due to the discharging, which induces a magnetic field

anyway just a guess but the currrent & the changing e field might geberate cancelling b field. this is just at a glance so .. i got an exam on this stuff in about a week so i might take a bette rlook at this later tonight

i should have read a little closer, but a "weakly conducting dielectric material" DOES NOT imply a current whatsoever. paper is a "weakly conducting dielectric material."

Well, the problem does say it has a current, running radially outward. The dialectric could be something like carbon...weak, but still conducting (ever-so-slightly).

I can see there not being a magnetic field. If current is radially out, i can't see what direction B-field could be in. If it's radially outward, then it diverges, violating Guass's law for B-fields (integral (B*da) = 0). If it's in the phi direction, it would seem to be kind of odd...it might violate faraday's or something. I could be wrong.

 

[RaynorWolfcastle]

GAH!!! Sounds like my cal class! Down with harmonic functions! FWIW, I don't see how this is different from parallel-plate a capacitor, but then again my Electro-Magnetic Fields class isn't until next semester.

Very weakly conducting just means you have some leakage current (as is the case in all practical capacitors). Just some thoughts, I'm an EE student not a phys student.