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From the research notes of Francis Gibson [bold added by editor]:
"Fig 2 [above] shows how we measured the presence of this motional E field. A highly insulated, stainless steel capacitor was placed around the center of the generator. The inner capacitor plate was connected to the heavy coat of conductive silver, shielding the rest of the generator and then grounded. The outer capacitor plate was connected to the input head of a Keithley 640 Vibrating Capacitor Electrometer. This particular electrometer with its high shunt resistances and its vibrating capacitor seemed ideal for this purpose. The generator with its capacitor and the head of the electrometer were then placed inside a stainless steel cabinet. All the connecting wires between the electrometer head inside the box and the galvanometer outside the box were electrostatically shielded, as well as the leads to the generator from the power supply. Everything was grounded through a terminal on the electrometer.
Now, we were ready to energize the generator with up to thirty amps of current from our power supply and measure the motional E field on the outside. The predicted value of the measurement was in the low microvolt region. Dr. Hooper, through working in college physics laboratories for over forty years, was well aware of the many problems associated with taking measurements in the microvolt region, and we had to test for and guard against them all. Our greatest problems came because we were unaware of the tendency for an electrostatic field to be generated equally and oppositely to this motional E field, and how frequently this phenomenon occurs. One time when we used one thick capacitor plate and one thin one, we discovered that the motional E field set up an electrostatic distribution within the thick capacitor plate, and reversed the charge on the outer plate. When capacitor plates of equal thickness were used the motional E field measurement was always positive." |
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Another problem we had involved the unbalance of our power supplies, we used two power sources: our own specially built one, designed to rectify 220 AC voltage to low ripple DC voltage, providing a maximum of 275 DC volts and 30 amps, and occasionally, 12 volt car batteries connected in series to compare results. At one point we discovered that when the current from the power source entered from one direction, the measurement of the motional E field was less than when it entered from the other direction Here, in Dr. Hooper's own words, is how he accounted for this problem, "The question arose as to why there would be a difference in readings because of an unbalance in the power source, as the inner capacitor plate is grounded, and the law is that there would be no electrostatic charge on the outside of a grounded enclosure. The interesting thing is that the only answer seems to lie in the fact that there is a motional E field present. If there is an unbalance on the inside of the container due to an unbalance in input voltage, the normal thing would be for charge to flow through the ground wire to balance the charge on the inside of the container. However, if the motional E field was acting in the ground wire in one way, it would oppose the flow of electrons toward the shield and, therefore, would allow an electrostatic charge to remain on the inner capacitor plate and affect the readings." We had to realize the significance of the fact that this field permeates everything.
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