Hi
There is a source that is making the current to flow. This source might be a battery or a generator or turbine, watever it may be. This source creates the voltage diff. that makes the current to flow. Therefore the work done comes from this source and the form can be varied like chemical for battery, or mechanical for turbine etc.
						

							
If the current in both conductors flow in the same direction, they will attract each other, whereas if the current are in opposite direction, they will repel each other.



This force is due to the interaction between the magnetic field of the 2 conductor. The figure below shows the catapult field produced by 2 current carrying conductors when their current is in the direction or opposite direction.




Faraday's law states that a changing magnetic field induces an electric field. So, the moment the current is allowed to pass in the two wires, a magnetic field is created in a region where there was none previously. This change induces an electric field which is responsible for the work done on and by the wires.