Number 3.
When you have two parallel wire and the charges are moving, they create a magnetic field around the wire (right-hand rule, thumb points in the direction of current).
If you want the math, here ya go:
F: magnetic force on the wire, L: length of the wire I: current in one wire I': current in other wire r: distance of the wire.
As we can see, two wires that has current through it will generate a force on each other.
When you have two parallel wire and the charges are moving, they create a magnetic field around the wire (right-hand rule, thumb points in the direction of current).
If you want the math, here ya go:
F: magnetic force on the wire, L: length of the wire I: current in one wire I': current in other wire r: distance of the wire.
As we can see, two wires that has current through it will generate a force on each other.
