EMF meters measure electromagnetic fields produced by electrical current, wiring, devices, appliances, power systems, and nearby electronics. K2-style meters make those field changes visible through simple lights.

Wall wiring, outlets, breaker panels, phones, radios, battery condition, routers, appliances, power lines, nearby equipment, and investigator movement can all create readings or light responses.

Establish baselines, map walls and known electronics, repeat the reading, move the device, compare with another meter if available, and log the exact time and location before interpreting the response.