When troubleshooting a lighting problem in an existing home, the home technology integrator differentiates between low-voltage and high-voltage lighting control by examining the:
A Certkiller technician is on-site to configure a home security alarm system. The technician needs to create a configuration that alerts the off-site customer monitoring center whenever the front and side doors are armed and opened. Which of the following devices does the technician need to install on the doors to have them trip the alarm?