# Calculate force on Permanent Magnet near a Paramagnetic surface

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1. Feb 25, 2016

### DeathCheese

Hello all, new here but plan to stick around for a while. I am currently trying to make a sensor that can detect if a material below it is paramagnetic. I believe paramagnetic is the proper term, but it needs to detect if the force exerted by permanent magnet is above a certain threshold. The setup is simple with a permanent disk magnet sitting on a force sensor with an air gap between the force sensor and the paramagnetic surface. Anyways, if I know the following parameters, can I calculate the force, or am I being naive?
• Magnetic Field Strength (B)
• Height of magnet (h)
• Distance between magnet and surface (d)
• Magnetic Susceptibility of surface (X)
Not sure if it's important but I'm assuming the surface being detected has an infinite area due to its size compared to the permanent magnet and sensor.

I appreciate any and all help, note I'm not a physics major so this might not be as difficult as I am making it. Thanks in advance!

2. Feb 25, 2016

### DeathCheese

So I found the formula for magnetic flux density of a cylinder magnet. I guess once I find the flux density it should be pretty easy to find the force exerted. If Im missing anything let me know please.