85. (a) Since GEpoints down and we need an upward electric force (to cancel the downward pull of gravity), then we require the charge of the sphere to be negative. The magnitude of the charge is found by working with the absolute value of Eq. 22-28: 4.4N||0.029C150 N CFmgqEE====, or 0.029 C.q= −(b) The feasibility of this experiment may be studied by using Eq. 22-3 (using kfor 1/4πε0). We have
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