What distinguishes “impedance” from “characteristic” impedance? A 1-foot length of RG-8X coax has a characteristic impedance of 50 Ohms. But does that cable present a 50 Ohm resistance to DC current flow? Can you describe the current flow that exists on such a coax cable if the end is open?
When you understand characteristic impedance, you can answer the above questions.
Please view the 3-minute video below where Wes Cardone (N8QM) illustrates characteristic impedance with animation.