Question

Millikan's oil drop experiment suspended a charged oil drop in an electric field.
By measuring the size of the drop and using the oil's density, the weight of each drop
could be calculated. This allowed the charge of each drop to be found, which was
always found to be a multiple of the charge e (1.6e-19 C). Thus, the electron was
found.
During one experimental trial, the weight of the oil drop was found to be 1.9e-15 N
and the electric field strength was 6.0e+3 N/C.


What was the size of the oil drop's charge?

Answer 1

Set the force of gravity (mg or n*e*g) equal to the electrostatic force E*ne