How does S Pen (Samsung) show cursor on screen? I would like to know how does samsung android os show the pen cursor when I took the pen out and point over screen without touching the screen? It is a miracle for me. I cannot find any sources.
Break it down-How does the S pen work? offers a nice explanation along with a link to video too


S pen pulls power from the device wirelessly

  Electromagnetic field that provides power to the pen can also be used to calculate its position relative to the screen. This, along with information from the S Pen button and the nib on the end are what is used to determine what the user it doing with the S Pen.

Pressure sensitivity is built in the stylus
To summarize


  An electromagnetic field is generated from a circuit behind the screen. The S Pen picks this up and uses it to power itself and figure out its position relative to the screen. It sends this, along with information from the S Pen button and the nib at the end, back to the Note.



Edit: Video in linked post makes it clear ascend easy to understand