Monroe Electronics Electrostatic Fieldmeter - Static Monitor - model 177A - Manual (Page 66)

APNE-0016 65
Figure II-2
Monroe Model 1036 Fieldmeter Probe
Electrostatic fieldmeters measure electric field strength by non-contacting means. All the
charged objects, voltage sources, and grounded conductors (including the fieldmeter probe
housing) in the general area affect the electric field strength measurement. The fieldmeter
measures the electric field strength only at its aperture. It does not have a viewing angle
and it does not see the web or object directly in front of it as a separate entity. This can be
demonstrated by measuring the electric field of an insulating sheet with a hole in it.
Figure II-3
Insulating Sheet Electric Field Demo, Top View
The field over the hole will not be zero even though there is no charge directly in front of the
probe head. This is because the electric field at the probe aperture is a function of each
charge on the sheet, and is also a function of the concentration of field due to the grounded
probe itself.
Place a charge on an insulating
sheet with a hole cut out of it
(hole to be larger than probe) .
Measure the electric field over
the sheet (a). Move the probe
over the hole and measure the
field again (b).
The measured field strength in
(b) will be less than in (a), but it
won’t be zero.
Probe
Probe Hole
Hole
(a) (b)