Looking at the back of my pickups, I noticed that the bottoms of the screws are in direct contact with the metal mounting plate. Since this plate is grounded, does that then mean that the screws are also grounded? If so, how does that work?
the emf/current comes from the coils, which are electrically insulated from the screws. The screws are essentially magnets, providing a magnetic field which changes with string vibration, then it is picked up by the coils with emf being -dφ/dt or -Ldi/dt