At last electric fields are made visible!  

The E-Field Detector is a sensitive instrument designed to facilitate hands-on investigations of the effects of positive and negative electrical charge. The probe of this detector can "sniff out" unknown charges, demonstrate charging by induction, and even prove the inverse square dependence of Coulombs Law. Not only does the E-Field Detector indicate if charge is present, it can also determine the sign and magnitude of the charge present. An LED display on the top of the instrument lights up red when positive charge is detected and blue if negative charge is present. More LEDs will light up as more charge is detected, allowing for qualitative investigations of charge.  This clever device works both as a lecture demonstration and as a laboratory apparatus. The back plate of the E-Field Detector houses ports so a voltmeter may be attached.