At an atomic level, electromagnetic fields are what makes electricity work. In a previous video, Electricity and Magnetism, Karen talks about how they work together in electronics. In this video, Karen introduces a sensor that is triggered by magnetic fields, the hall effect sensor. While Karen has used reed switches, an electromechanical magnetic switch, in an escape room puzzle in a previous video, here she shows how hall effect sensors use magnetic fields as either digital (on/off) or analog (linear) switches that are purely electrical with no moving parts. This video continues the exploration of electricity and magnetism also covered in Intro to DC Motors and Intro to Speakers & Microphones.