Go Back   Physics Help Forum > High School and Pre-University Physics Help > Electricity and Magnetism

Electricity and Magnetism Electricity and Magnetism Physics Help Forum

Like Tree4Likes
Reply
 
LinkBack Thread Tools Display Modes
Old Jun 8th 2019, 08:10 AM   #1
Junior Member
 
Join Date: Jun 2019
Posts: 3
Dipole magnet as a cathode

Hey physics professionals.
This is a somewhat odd request for info but I thought I'd run it up the flagpole here, see who salutes; I'm aware a dipole magnet can't be a cathode, what I can't find is any specific information as to why. The kicker is I'm going to attempt to explain this to an audience that likley wont understand physics so I'll need as close to a layman term as I can get.
Thanks in advance to anyone willing to help. Mike
Gentley is offline   Reply With Quote
Old Jun 8th 2019, 05:32 PM   #2
Senior Member
 
Join Date: Mar 2019
Location: cosmos
Posts: 307
Talking

@Gentley:
This semi - tramp is not a physics professional but only a physics curious, so he salute to any physics flagpole.
I think that you know the physical principle clearly: the magnetic field of the magnet will deviate the electron from the normal moving route in eletric field.
But what you want is a vivid and philosophical analogy, isn't it?
Attached Thumbnails
Dipole magnet as a cathode-029876.jpg  

Last edited by neila9876; Jun 8th 2019 at 05:35 PM.
neila9876 is offline   Reply With Quote
Old Jun 8th 2019, 06:02 PM   #3
Forum Admin
 
topsquark's Avatar
 
Join Date: Apr 2008
Location: On the dance floor, baby!
Posts: 2,681
Originally Posted by Gentley View Post
Hey physics professionals.
This is a somewhat odd request for info but I thought I'd run it up the flagpole here, see who salutes; I'm aware a dipole magnet can't be a cathode, what I can't find is any specific information as to why. The kicker is I'm going to attempt to explain this to an audience that likley wont understand physics so I'll need as close to a layman term as I can get.
Thanks in advance to anyone willing to help. Mike
Yes and no. A cathode is a device that attracts electrons. Since a dipole magnet has no electric charge on it to attract electrons it can't be a cathode.

On the other hand, if the dipole is located in a stream of plasma then the magnetic field will indeed move the charges in the plasma so we see a migration of electrons to one pole of the magnet. Technically not a dipole but on a small scale (compared to the physical size of the magnet) one end of the magnet can look like a cathode.

-Dan
__________________
Do not meddle in the affairs of dragons for you are crunchy and taste good with ketchup.

See the forum rules here.
topsquark is offline   Reply With Quote
Old Jun 8th 2019, 07:17 PM   #4
Senior Member
 
Join Date: Mar 2019
Location: cosmos
Posts: 307
Question

@Dan:
What's the term "dipole magnet" mean exactly in English? I feel it means "a magnet with two poles"?
neila9876 is offline   Reply With Quote
Old Jun 8th 2019, 07:48 PM   #5
Forum Admin
 
topsquark's Avatar
 
Join Date: Apr 2008
Location: On the dance floor, baby!
Posts: 2,681
Originally Posted by neila9876 View Post
@Dan:
What's the term "dipole magnet" mean exactly in English? I feel it means "a magnet with two poles"?
Yes, magnets have dipole moments. North and South, like a compass. (There have been no deteced monopoles.) But you can have higher polar moments as well by placing a system of magnets in the right positions.

-Dan
__________________
Do not meddle in the affairs of dragons for you are crunchy and taste good with ketchup.

See the forum rules here.
topsquark is offline   Reply With Quote
Old Jun 9th 2019, 12:08 AM   #6
Senior Member
 
Join Date: Mar 2019
Location: cosmos
Posts: 307
Red face

@Dan:
What's the difference between "dipole magnet" and "magnetic dipole" in English?
neila9876 is offline   Reply With Quote
Old Jun 9th 2019, 12:30 AM   #7
Senior Member
 
Join Date: Apr 2017
Posts: 486
I don't see why a dipole magnet cant become a cathode ....

Just wrap the negative wire around a magnet , put it in the solution and it becomes a cathode ...

topsquark and neila9876 like this.
oz93666 is offline   Reply With Quote
Old Jun 10th 2019, 10:00 AM   #8
Senior Member
 
Woody's Avatar
 
Join Date: Jun 2016
Location: England
Posts: 890
I think Topsquarks original interpretation of the cathode as in an old cathode ray screen is what the OP was thinking of.

The problem then would be that you want the electrons to travel in as straight a line as possible away from the cathode,
so that you can subsequently bend it in a very precise controlled manner to create the picture on the screen.

However if the cathode were magnetic, the electrons it emitted would follow a curved path through the magnetic field it generates.
topsquark likes this.
__________________
~\o/~
Woody is offline   Reply With Quote
Old Jun 10th 2019, 05:25 PM   #9
Senior Member
 
Join Date: Mar 2019
Location: cosmos
Posts: 307
Talking

That flagpole seems to want a tabloid description for his layman audience...
neila9876 is offline   Reply With Quote
Old Jun 11th 2019, 02:10 PM   #10
Junior Member
 
Join Date: Jun 2019
Posts: 3
Thanks for the replies.
Yeah I wanted vivid, philosophical and thought I had it.. then the goal posts got moved; from just a magnet to an electromagnet.
Here my knowledge falls down. While I know the electromagnet concept, I can't say I know if a dipolar magnet can be sustained as the load in a circuit, now I don't mean wrapping the conductor around a ferrite type of circuit, I mean the ferrite as the conductor if you see what i mean. I'd instinctively go with no because I doubt a dipole field could form, other than the field be some degree out of phase following the neutron or electron.. but then I think plasma ball and I have no idea if they are possibly dipolar if even in theory or if they're even magnetic at all.
Think I might retire myself from the planned discussion in all honesty, the more I read the fewer answers I have, I just end up with more questions.
Gentley is offline   Reply With Quote
Reply

  Physics Help Forum > High School and Pre-University Physics Help > Electricity and Magnetism

Tags
cathode, dipole, magnet



Thread Tools
Display Modes


Similar Physics Forum Discussions
Thread Thread Starter Forum Replies Last Post
electric dipole ohm Electricity and Magnetism 3 Sep 5th 2016 10:02 AM
Cathode-Ray Tubes and Electric Fields ZergLurker Advanced Electricity and Magnetism 1 Feb 24th 2010 09:44 PM
electric dipole tag16 Electricity and Magnetism 1 Sep 22nd 2009 11:11 PM
Electric dipole Apprentice123 Advanced Electricity and Magnetism 2 May 17th 2009 06:41 AM
CRO Cathode Ray Oscilloscope werehk Waves and Sound 1 Jan 18th 2009 12:24 AM


Facebook Twitter Google+ RSS Feed