Millikan measured the electron's charge by observing tiny charged oil drops in an electric field. each drop had a charge imbalance of only a few electrons. the strength of the electric field was adjusted so that the electric and gravitational forces on a drop would balance and the drop would be suspended in air. in this way the charge on the drop could be calculated. the charge was always found to be a small multiple of 1.60 × 10-19 c. find the charge on an oil drop weighing 1.00 × 10-14 n and suspended in a downward field of magnitude 2.08 × 104 n/c.