How Does X-Ray Ionisation Impact Millikan's Oil Drop Experiment?

[curious bishal]

What is the use of X-ray in Millikan's oil drop experiment? It ionises the oil but what does the ionisation help in? If it creates charge, then the oil's charge keep on increasing it creates error in calculation as the oil drop is attracted upward after sufficient amount of charge.

 

[Simon Bridge]

The X-ray tube was used to charge the oil drops.
There is a limit to how much charge can be removed from the drop by x-rays and, anyway you can always turn the tube off before doing the experiment.

 

[sophiecentaur]

Without something to charge the drops, there would be no experiment.