How to make gradient Magnetic field?(blueprint)

I wnat to make gradient magnet filed.
but when i use force, it active same force in all set Rad.

if i set Rad 1000 / Fc 10000 then in 1000Rad everywhere Fc is 10000

I want to make Fc depend on Rad, closer is more powerful.

anybody help me please??

one easy way would be to specify a radius and then
check if the distance is inside the radius and divide the distance by the force

thats the basic way i managed it in some old projects.

What kinds of force did you us? Please,