- An electric field is the force resulting from electric charges
- Field strength is measured in volts/meter (V/m), and is inversely proportional to distance from the source, i.e. at twice the distance the field strength is halved
- Field strength may also be expressed as Power Density in Watts/meter2 (W/m2). Power Density is proportional to the inverse of the square of the distance from the source, i.e. as twice the distance power density is a quarter