What is the resistance of short circuit, and open circuit

The resistance of a short circuit is essentially zero. This is because a short circuit is a path of least resistance for electric current to flow. It bypasses the load (like a light bulb, for example) and connects the two sides of a power source together. Because there is very little resistance, the current flow can become dangerously high.

On the other hand, the resistance of an open circuit is infinite. An open circuit is one where the path for the electric current to flow is broken, usually by a switch that is off. Because there is no path for the current to flow, there is no current. In terms of resistance, this is considered to be infinite resistance.