Calculating the requirements for magnetic levitation

[downtownjapan]

Hi everyone,

I am interested in using an electromagnet to repel a permanent magnet and lift it up, and I am thinking about how to go about calculating the required magnetic field strength of the electromagnet for this operation.
I have attached a rough conceptual drawing showing the electromagnet positioned underneath the permanent magnet, both enclosed in a tube to control the range of movement of the permanent magnet.
In the the section labelled Pic 1, the permanent magnet sits on top of the electromagnet, which is switched off. The permanent magnet is attracted to the ferrous core of the electromagnet.
In the section labelled Pic 2, the electromagnet is turned on. It repels the permanent magnet, lifting it up.

I am interested in calculating how strong the electromagnet needs to be in order to counter the attraction of the permanent magnet and repel it successfully.

Does anyone want to comment on the proposed following formula to calculate the required electromagnet field strength?

Required electromagnet field strength = permanent magnet's field strength + permanent magnet's weight

Am I on the right track with this reasoning?

Actually I studies very little science, and have never studied any physics at all. All of what little understanding I have comes from places like this forum - so any comments or suggestions would be much appreciated.

Thanks everyone!

 

[CWatters]

Check the units in your equation :-). It's not always easy to calculate the force between two magnets but perhaps see..

http://en.wikipedia.org/wiki/Force_...ween_two_nearby_magnetized_surfaces_of_area_A