No every river starts at its own unique geographic point on Earth.
The river is formed by the confluence of the Allegheny and Monongahela rivers at Point State Park (called the "Point") in Pittsburgh, Pennsylvania. It joins the Mississippi River at Cairo, Illinois. The native Americans considered the Monongahela to be the same as the Ohio and the Allegheny as a branch.
A river is a body of water. An island is a body of land. A river flows from point A to point B. An island stays in the same position.
not always
Waterfall is the term for a gravitational fall of water in a river. (water fall.) It forms quite the same way as canyons: The river carves through the berg or what ever, but at one point the ground is weaker, causing the river to carve faster. Making a rapid change of elevation. Water fall s down at that point.
No. Every point on a contour line has the same elevation.
A circle
Most rivers start from the sea. The point where the river joins to the sea is called the mouth. I guess they end when the ground eventually gets high enough so that the water comes to a halt. Or, it could turn into a lake, but the principle is the same. Sometimes they come to dams too :)
Current. There is only one path that current can take through the circuit, so the current must be the same at every point.
Kirchof's Law - the voltages are measured between the same starting-point and end-point.
yeah if there inhabitants agree
... center of the circle.
Yes.