How can i make this shape of magnetic field in grasshopper primer?

[HS_Kim]

Attractors exercise in Grasshopper Primer

Hi guys, i was browsing the GH Primer and this exercise caught my eye, i was trying to replicate and i was succesful in the point/vector/orientation (the little #3) exercise but my brain stopped in the others particular cases. I tried with Curve CP but i didn’t work. Could please help me to understand it better. Thank You Very Much in Advance Daniele. [primer01][primer02]