That is a good point, I take back what I said about the number of lines of force.
Here are a few related questions I am using over
Small magnet versus large magnet. Are the NUMBER of lines of force the same , but the larger magnets lines of force are stronger?
In attraction it appears some...
Thank you Kuruman, and I take your point. I think my point is I suspect just looking at the shape of the fields involved in attraction versus repulsion that there are two different formulas at work. A simple way to think of it is that many of the lines of force in repulsion go off into space...
The direction can be reversed by reversing the flow of current thru the electromagnet.
Have a look at the actual equations for two bar magnets discussed in this forum a few years back at this location
https://www.physicsforums.com/threads/force-of-attraction-between-two-bar-magnets.707237/
Equations of attraction or repulsion can get very complicated when the field shapes and densities are not identical. Intuition would hold the forces to be the same, but in on closer examination the field shape of two repulsing magnets looks entirely different from two attracting magnets. I...
Thank you both
Very interesting ideas.
Charles , I was wondering about the very thing you mentioned above. In our test apparatus , we are using a very wide , but quite thin permanent magnet..3 inches wide , and 1 inch deep , in other words the axis of magnetization would be a line connecting...
I have a good experimental rig to test these things, I feel like something isnt set up right.
If you have drop box you can have a look. This is a test of repulsion between a electromagnet with a steel core and a permanent magnet , but you can get a sense of the test apparatus...
easily enough i found a reference http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/elemag.html
The shapes of the fields of a bar magnet and an air core electromagnet are the same ssuming the length of the coil is the same as the length of the bar magnet
Thank you CWatters and again to you Charles.
A few clarifying comments and questions:
Do we agree that two identical permanent magnets will attract each other with a pull force that is some product of the strength of the two opposing fields diminished by the square of the distance , and that...
Thanks Charles
Nice to hear from you again
I understand that a core makes a coil much stronger
I dont think i explained my main question very well
Im saying in our experiments the hold force of the air core electronagnet against a steel plate was calculated and then a small permanent magnet...
We know that the attractive force between the opposing poles of identical permanent magnets is a product of their field strength and that the total force diminishes as the distance between them increases. If we assumed the magnets to be point entities, the formulation is the same as that for...
Hi
Thanks again
I need to absorb your comments and do some reading on the topic before I reply to one particularly interesting comment ( free electrons would form pairs with opposing spins) (( but not at first ?))
Thank you Gan_Hope for your very cogent explanation.
I do have two clarifying questions if you have a few minutes
First,I am interested in hearing more about the process in the exchange interaction. Are we saying here that the external magnetic field is contributing energy that allows an...
I am having difficulty thinking through how a ferromagnetic substance is permanently magnetized.
I think I understand that when for example a sample of iron is heated above it curie temperature and then exposed to an external magnetic field , the sample will become permanently magnetized. The...
Hi Charles
Trying to work the equation and replicate your numbers. I am getting about 5 pounds of force using your inputs( I think). If you have a moment , could you look this over and see where I have gone astray. I did assume you were expressing the magnet strength in gauss. I also do not...
Charles
Thank you for the above.Very helpful
I will be setting up test with the two magnets and the spring balance, so I will let you know the results and will email you directly ( assuming I can do that , I have not checked yet). Will probably be about a week until I have the answer.
As you...