Summary: This is the simplest physigram, just two states for the switch.  It also demonstrates an exposed state, one-to-one mapping between the switch states and the underlying logical state (light bulb).

One of the simplest examples of a physical device is a simple on/off light switch. The switch has exactly two states (up and down) and pressing the switch changes the state.  In the physigram there are two states, the ‘UP’ state when the switch is up and the ‘DOWN’ state when it is down!

A switch of this sort could be used for unusual applications: for example, we might use the length of time it is down to trigger some action.  However, that would be rare; the normal use of such a switch is to connect to a light bulb or other form of electronic equipment, to switch it on or off.

The diagram below shows the way the physigram states map one-to-one to the light bulb states.