Answer:
Contact tube
Explanation:
Because of the constant-potential power supply, the welding current will change as the distance between the contact tube and the work changes.
Contact tube is a device which provides electric current to a continuous electrode during welding process
it is made of a small copper alloy which enable it to transfer current to the electrode and channel the electrode towards the work( i.e the wire becomes energized by contact with the copper which then transfer current from the potential power supply to the welding
