If circuit is built without resistor and fingertip bridges the gap the lamp will light. Water will also turn the circuit on, so it could be used to monitor any place that should stay dry. The lamp could be replaced by a sonalert for an audible alarm.
An interactive circuit built in the DCACLab online simulator by Sam Watson. Open it to run the simulation and measure it.
Open in the labEmbedThe simulation runs as a demo that pauses after two minutes; open it in the lab to keep going.
Cite:
Watson, S. (2014). If circuit is built without resistor and fingertip bridges the gap the lamp will light. Water will also turn the circuit on, so it could be used to monitor any place that should stay dry. The lamp could be replaced by a sonalert for an audible alarm. DCACLab. https://dcaclab.com/circuits/9841-touch-activated-switch