EMF Detector: EMF is a short for electromagnetic field, while a device that is used for detecting emf is called emf meter, indicator, finder, scanner, tester, reader or what ever the term may be used to justify the function of device. EMF Detector App: EMF Detector App or EMF measurement App for android is simply an App that uses the Android build in magnetic field sensor to detect the emf. So the above definitions for emf meter are pretty much enough to understand what emf detector & reader