Repulsive force of an electromagnet and a magnet

[Inventor1]

I have been researching for quite a while about this subject and I only got more confused. I want to evaluate the repulsive force between a magnet of 52 MGOe and an electromagnet. The goal is to generate a repulsive force of say 75 Newtons.

So I am using a neodymium magnet N52 how can I figure this out? its a vital information for my theoretical project.

 

[Charles Link]

I foresee one potential problem: Maybe it's of no consequence but worth considering: If you start with the "unmagnetized" electromagnet with an iron core, and bring the permanent magnet close to the iron core, you will magnetize the iron core in the same direction as the permanent magnet. You will then have a very strong attractive force. The current of the solenoid of the electromagnet may not be sufficient to reverse the magnetism of the iron core, so that you might not get the repulsion that you are hoping for.

 

[Inventor1]

I foresee one potential problem: Maybe it's of no consequence but worth considering: If you start with the "unmagnetized" electromagnet with an iron core, and bring the permanent magnet close to the iron core, you will magnetize the iron core in the same direction as the permanent magnet. You will then have a very strong attractive force. The current of the solenoid of the electromagnet may not be sufficient to reverse the magnetism of the iron core, so that you might not get the repulsion that you are hoping for.

It doesn't matter as long as I obtain motion.in a direction or another. My math will vary but the resulting effect will be the same.

 

[Charles Link]

It doesn't matter as long as I obtain motion.in a direction or another. My math will vary but the resulting effect will be the same.

It's much easier to get an attractive force, but I don't know how much stronger of attraction you will get with the addition of a solenoid. The attractive force is also something you won't be able to turn off.

 

[Inventor1]

It's much easier to get an attractive force, but I don't know how much stronger of attraction you will get with the addition of a solenoid. The attractive force is also something you won't be able to turn off.

The way you are talking, it is almost like you know what I want to do or partially. The fact is that the magnet will never reach the core. And I am planing on keeping the magnet's field concentrated with Giron material or mu metal inside a magnetic chamber. I have perform some experiments and i am close from what I want. but I need to figure the proper force. and that is where I am blocked.

 

[Charles Link]

The way you are talking, it is almost like you know what I want to do or partially. The fact is that the magnet will never reach the core. And I am planing on keeping the magnet's field concentrated with Giron material or mu metal inside a magnetic chamber.

Theoretical calculations of these forces between magnets doesn't quite fit the standard textbook type problem. You can google the subject "forces between magnets", but for the most part, that will only give you rough estimates. There may be a couple of people who have a lot of "hands on" experience with doing this kind of thing experimentally, but I haven't really done much of that sort of thing.

 

[Inventor1]

The f

Theoretical calculations of these forces between magnets doesn't quite fit the standard textbook type problem. You can google the subject "forces between magnets", but for the most part, that will only give you rough estimates. There may be a couple of people who have a lot of "hands on" experience with doing this kind of thing experimentally, but I haven't really done much of that sort of thing.

Well if you think someone can be of help, I am all ears. Thanks

 

[Charles Link]

Here is something that can help to get rough estimates. https://en.wikipedia.org/wiki/Force_between_magnets You can use $B_o=1.0$ Wb/m^2 (approximately) and $\mu_o=4 \pi$ E-7. (I'm looking at the formula for the "Force between two bar magnets").

 

[Inventor1]

Here is something that can help to get rough estimates. https://en.wikipedia.org/wiki/Force_between_magnets You can use $B_o=1.0$ Wb/m^2 (approximately) and $\mu_o=4 \pi$ E-7. (I'm looking at the formula for the "Force between two bar magnets").

Technically, the magnet goes where ever the current flows because the core is already magnetized when the current is turn on and even if the current is turned on after, the magnetic would flip the current direction. If the magnet is placed on a metal plate, says at the right end of the ferromagnetic core then at left side, we power a solenoid,the magnet should follow the pulling magnetic field and release itself from the plate to the right to set itself onto the solenoid core. This should happen no matter the current passing and generating the electromagnetic field. That is why I am trying to calculate using Coulomb's Law

 

[berkeman]

I want to evaluate the repulsive force between a magnet of 52 MGOe and an electromagnet. The goal is to generate a repulsive force of say 75 Newtons.

Why not just use two electromagnets? That will give you a lot more control over the forces and directions...

 

[Charles Link]

Technically, the magnet goes where ever the current flows because the core is already magnetized when the current is turn on and even if the current is turned on after, the magnetic would flip the current direction. If the magnet is placed on a metal plate, says at the right end of the ferromagnetic core then at left side, we power a solenoid,the magnet should follow the pulling magnetic field and release itself from the plate to the right to set itself onto the solenoid core. This should happen no matter the current passing and generating the electromagnetic field. That is why I am trying to calculate using Coulomb's Law

Except that as mentioned in post 2, this could be very problematic. $\\$ @berkeman had a very good suggestion in post 10. I do see a possibility even with that case though in trying to achieve repulsion that one electromagnet or the other may become dominant and magnetize the whole system in a single direction, creating attraction between the cores, regardless of the solenoid current running in the reverse direction: In general, the magnetic fields that occur from the iron cores are 100 to 1000 times greater than the magnetic field that the current in the solenoid generates. If one of the cores gets the upper hand, in the magnetic field that occurs in the other electromagnet, from a combination of the magnetic field from the solenoid current that is trying to magnetize the core plus the magnetic field from the adjacent electromagnet (which may be stronger and is in the opposite direction), it will basically behave as if the solenoid current wasn't present in that electromagnet. The adjacent (dominant) electromagnet will then magnetize the whole system in one direction.

 

[Inventor1]

Except that as mentioned in post 2, this could be very problematic. $\\$ @berkeman had a very good suggestion in post 10. I do see a possibility even with that case though in trying to achieve repulsion that one electromagnet or the other may become dominant and magnetize the whole system in a single direction, creating attraction between the cores, regardless of the solenoid current running in the reverse direction: In general, the magnetic fields that occur from the iron cores are 100 to 1000 times greater than the magnetic field that the current in the solenoid generates. If one of the cores gets the upper hand, in the magnetic field that occurs in the other electromagnet, from a combination of the magnetic field from the solenoid current that is trying to magnetize the core plus the magnetic field from the adjacent electromagnet (which may be stronger and is in the opposite direction), it will basically behave as if the solenoid current wasn't present in that electromagnet. The adjacent (dominant) electromagnet will then magnetize the whole system in one direction.

Would that act like a river carrying a boat? I mean if if I had a Solenoid at both ends of the ferromagnetic core and the magnet stoke to the right and induce a charge to the solenoid on the left would the magnet be pulled to the left? See the magnetic field generated by the left solenoid will induce the right one and it will also generate an its own magnetic field. Its a conundrum.

 

[berkeman]

Its a conundrum.

It's worse than that. I'm not able to parse your post...