I want to know why this happens in terms of whats going on at an atomic scale with the flowing electrons in the metallic bond. Thanks
First I thought you were looking for an explanation of diffusing electrons in a wire, but I think you are looking for an explanation of ohms' law: VIR or as you indicate R V/I. What you are missing is that the voltage is not constant. The resistance is fixed from the physics of the conductor. In a circuit you can have a current source where you control the amount of current. In this case if there are no components changing the resistance, the voltage drop across the resistor changes as you change the current. On the other hand, you could have a voltage source like a battery. The voltage drop across the resistor can not change. It is equal to the battery's voltage, but if you change the resistance, the current will change. Hope that makes sense. If it is really the former you were looking for I think it can be explained by looking at the effect of heat on the wire and keep in mind that electrons aren't zipping from one end of the wire to the other even in a DC circuit.
think of of it like the bypass in a circulate. the present is the bypass of electrons and the resistance is the resistance to this bypass, like an impediment blockading the path of the water.
Your clarifying statement doesn't make sense. Generally speaking, the more a conductor is cooled, the lower will be its resistance. If the current is increased, heat will be generated that in turn increases the resistance. Conversely, if the current is reduced, less heat is generated so the resistance will decrease. (This principal is used to produce super conductors, some of which when cooled to near absolute zero show virtually zero resistance.)
Because resistance increases with temperature . Dunno how this happens on the atomic scale , sorry.
Temp. increases with increasing current because the wire dissipates more electrical power. P VI I^2*R. At normal temperatures a higher temperature means more resistance because more thermal motion of ions causes scattering of electrons. Scattering is random motion rather than the expected motion in the direction of (electron) current flow. From the ref., Near room temperatures, the thermal motion of ions is the primary source of scattering of electrons (due to destructive interference of free electron wave on non-correlating potentials of ions), and is thus the prime cause of metal resistance. If you are wondering about resistance behavior at lower temperatures, the ref. says At lower temperatures (less than the Debye temperature), the resistance decreases as T^5 due to the electrons scattering off of phonons. At even lower temperatures, the dominant scattering mechanism for electrons is other electrons, and the resistance decreases as T^2. EDIT: You said why does a decrease in the current cause an increase in the resistance; I think you're talking about some nonlinear effect that's typically associated with semiconductors, not metals.
