Re: How does ground loop voltage changes with ground loop impedance
It usually won't decrease the total induced voltage, but it will force most of the voltage drop to be at a specific point in the circuit. That way it can be dealt with by using differential signaling or isolators at that one location, instead of all over the place. The worst case is when the total impedance is so low that the induced emf is distributed throughout your circuit ground reference.
And sometimes the ground loop current itself matters, and must be attenuated with increased loop impedance, even if this does nothing for the induced voltage.