636 Period 3 Motor Final Practice Test

Oxidation at a copper connection raises the resistance at that joint. The copper oxide layer that forms is a poor conductor compared to clean copper, so it reduces the effective contact area and increases the contact resistance. In a loose connection, current has to pass through a smaller, uneven area, which concentrates energy as heat (P = I^2R). That extra heat can worsen the contact and accelerate further oxidation or loosening. So the result isn’t more conductivity or less resistance or no effect; it’s higher resistance that makes the joint heat up.