How does current flow even when there is no voltage difference?

Question

In bus bars, superconductors etc, where the drop is [almost] zero, how can current flow between points on them?

After all, current flows from higher potential to lower potential - isn't it?

Answer 1

there is a  voltage difference between two points on a buss bar in order for the current to flow.  Ohms law states that

Voltage = Current x Resistance

Voltage drop referrs to electrical loss due to the resistance.   So if you start out with a 100V source  and have a 1 volt drop across a buss bar that supplies current to a load then 99volts is available for the load to use.

Superconductors have very low resistance (nearly zero)  so if a buss bar has zero resistance there will be zero volts dropped across it. (Ohms Law)

Copper wire and buss bars still have some small resistance (not zero)

and when a large current passes through this small resistance then a voltage will be dropped across that resistance

1 Volt = 1000Amps x 0.001Ohm (copper  conductor)

0 Volt = 1000Amps x 0 Ohms (super conductor)

Answer 2

If there isn't any resistance, then there need be no potential.  The electrons are set moving by a magnetic field or potential which is then removed.   Only applies to superconductors.