Electrometer charge measurement

Medley (M4) working in vacuum also found that mercury became positively charged relative to nylon, mica, and Alkathene6 film. He obtained the contact by bringing a column of mercury up against a film of the other material, the back of which was covered with a stationary film of mercury connected to an electrometer, which measured the charge after the contact... 

During the connection of the samples to the electrometer charge loss to grounding was unavoidable. Thus, the current peaks appearing at 77°K. had to be ignored in interpreting the measured data. 

FIGURE 3-7 Net charge measurement Faraday cage (cup) with electrometer. 

Another electrification technique involves rolling a ball of test material for study in a cyhnder separated by an insulator. The two halves of the separated cylinder are then connected to an electrometer for measurement of the charge generated in the system. Peterson (1954) and Wagner (1954) have studied static electrification in this manner. Several observations may be made from these studies ... 

Consider a ball probe of a conductive sphere such as a stainless steel ball bearing which is connected to an electrometer. When the ball probe is placed in a flow system, the electric current induced by charge transfer between the ball and the flowing charged particles can be measured. The amount of current measured will vary with the particle velocity and particle mass flux. 

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