Ex:Region y <0 consists of a perfect conductor while region y > 0 is a dielectric medium (€,-1 = 2). If there is a surface charge of ps = 2 n on the conductor, determine E and D at т2 (а) А (3,-2,2) (b) В (-4,1,5)

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(1 )Region one z>0 consist of dielectric medium (er=4) (2)Region two z<0 consist of perfect conductor. Determine D&E at point (3,2,-3) and point (2,-1,3), if the surface charge on the conductor is equal to 8nc/m?

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)