When a switch is closed, it has __________ resistance and when open, it has __________ resistance.

When a switch is closed, it creates a continuous electrical path, effectively making the resistance very low or minimum. This allows current to flow freely through the circuit. When the switch is open, there is a break in this electrical path, resulting in extremely high or maximum resistance, which prevents current from flowing. Therefore, the correct understanding of a switch's operation highlights that a closed switch facilitates current with low resistance, while an open switch blocks current with high resistance. This concept is fundamental in understanding how switches control the flow of electricity in circuits.