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Reading Quiz Number 3

There are two identical metal disks of mass m = 7 g. One sits on a table. The other hangs by a string, 1 meter above the table. Each disk is neutral.

You start taking electrons from the lower disk, one at a time, and transferring them to the upper disk.

How many electrons must you transfer in order to cause the lower disk to rise up off the table? 

Answer:  about 1.7 x 10^(13) electrons

Creative Commons License Copyright © Michael Richmond. This work is licensed under a Creative Commons License.