In the early 1900's Robert Millikan discovered the peculiar property that charge came in little packets, no smaller than e = 1.602 x 10-19 C -- he had measured the charge of the electron. Here's (roughly) how he did it. He removed an electron from an initially neutral droplet of oil with diameter 0.5 ??μm. In a vacuum, he positioned the droplet between two metallic plates separated by 6 mm and fiddled with the potential (voltage) across the plates until the droplet would hover against the force of gravity. Droplets of this size with +e charge would hover, but only for a particular voltage (otherwise they would sink or rise). Given the parameters stated here, and the fact that the density of the oil was 831 kg/m3, what was the voltage that made the droplets hover?
In the early 1900's Robert Millikan discovered the peculiar property that charge came in little packets, no smaller than e = 1.602 x 10-19 C -- he had measured the charge of the electron. Here's (roughly) how he did it. He removed an electron from an initially neutral droplet of oil with diameter 0.5 ??μm. In a vacuum, he positioned the droplet between two metallic plates separated by 6 mm and fiddled with the potential (voltage) across the plates until the droplet would hover against the force of gravity. Droplets of this size with +e charge would hover, but only for a particular voltage (otherwise they would sink or rise). Given the parameters stated here, and the fact that the density of the oil was 831 kg/m3, what was the voltage that made the droplets hover?
(give your answer with 0.1 V precision)
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