A knife switch has a simple handle that swings back and forth to open or close a circuit. The switch itself is not covered with insulation. It is easy to see if the switch is open (on) or closed (off). The knife switch in the photos below could be used to turn off a power tool or other equipment.

A simple knife switch is good for doing experiments with electricity of low voltage. Dry cells have low voltage and are often used for these experiments. If you touch the metal of the switch, you should not get hurt when using very low voltage with dry cells!