Oil Drop Experiment

[Chris Dis3L]

In Robert Millikan's oil drop experiment, a fine mist of oil droplets are sprayed into a container with an electrically charged gas. The oil droplet's location is monitored by using a microscope as it passes between two charged plates. However, in the experiment, the oil droplets are also charged. The gas in the chamber is ionized by exposing it to x-rays, but what gives the oil droplets their charge and are they positively or negatively charged?

[Elena Saab 4A]

This is also confusing me. I think naturally oil is not charged so the experimenters must have altered it manually?

[Peichung Chou 1A]

The oil-drops were negatively charged through ionization with an x-ray. Thus, they were intentionally charged by the experimenters Millikan and Fletcher.