An experiment involving a conducting sphere that oscillates between two electrodes is described. Theory is presented that predicts a linear relationship between frequency and applied voltage for the system, regardless of electrode configuration. Data taken for several geometries is in good agreement with this theory. Some properties of the oscillator system, including its desirable characteristics as a high voltage voltmeter, are discussed.
A demonstration of the mercury-drag effect is presented as an example of transport phenomena in dilute gases, in which one gas or vapor diffuses through a second gas, creating a viscous drag on this gas. In the demonstration, mercury vapor from a pool of liquid mercury diffuses through nitrogen gas (pressure 10−5–10−4 Torr), passing through tubes of two different radii (0.69 and 0.33 cm) to liquid nitrogen-cooled cold traps. The pressure changes of the nitrogen gas on the mercury-deficient side of the cold traps is observed and compared with theoretical and experimental values from the literature. Possible reasons for differences are discussed.
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