## Electromagnetic and Magnetic Levitation

Hi!
I am setting up a levitation system and need to estimate the amount of voltage and current that is needed for a 2" dia. coil to produce 4800 Gauss. I don't have any restrictions/requirements on the core, number of turns, etc as long as it would produce 4800 Gauss with a 2" diameter. How can this be calculated? (I have spent a lot of time googling for such information, but I am pretty confused and didn't find how to calculate this)
Thanks!

active| newest | oldestSee the equation below, which I lifted from this paper.

To find the field strength in Tesla ( = 10,000 Gauss), multiply the number of turns in the coil, radius of the coil in metres, the current flowing and the permeability of vacuum (4pi * 10

^{-7}) together, then divide by ((the radius^{2}+ the axial distance from the coil^{2})^{1.5), then halve the result.}To find the number of turns and current, you will need to set B=0.48T (=4,800 Gauss), a=0.05 (2" = 5cm = 0.05m) and z=the required distance in metres and solve the equation. This could get a bit weird as you have a fractional power on the bottom of a fraction- get a large piece of paper and put your algebra hat on.

Alternatively, if you feel like doing groundwork to make your life easier later on, write a calculator in a spreadsheet that lets you plug numbers in and calculates the field, then play with the numbers until you reach something achievable.

u

_{0}is the permeability of vacuum, 4pi*10^{-7}or about 0.0000012566N = turns

I = current (Amps)

a = radius (metres)

z = axial distance from coil (metres)

insidethe coil, as opposed to the outside for magnetic levitation.^{2}term in the denominator is the distanceoutsidethe coil, along the polar axis. Inside the volume of the coil, you should take z=0 everywhere.I'm still curious how you arrived at the 4800 Gauss figure- I have no idea how to equate field strength with attractive/repulsive force in simple terms.

By the way, the u0 means the permeability of a type of core, right? So if I am to put an iron core, that would produce a greater magnetic field (if I am not mistaken?). I had a look on wikipedia's permeability on common materials chart : It seems that steel or ferrites would be a good option. However, I don't quite understand what its column labeled Magnetic Field means. It sounds like the material's permeability changes according to the amount of magnetic field applied to it?

_{My third thought was "doh!"}