Robert Millikan's Oil Drop Experiment

[cragar]

when Robert Millikan did the oil drop experiment to measure the charge of an electron .
they balanced the gravitational force of the oil drop with the electric field .
did they use F=qE , did they know how many electrons were in their oil drops .

 

[uart]

.
did they use F=qE

Yes, that and F=mg.

did they know how many electrons were in their oil drops .

No, they only knew that it was an integer multiple and they examined the charge on many individual drops to try and determine what number they were a common multiple of.

 

[cragar]

ok thanks for your answer .

 

[alxm]

In retrospect, it turned out Millikan also used a bit of http://www1.umn.edu/ships/ethics/millikan.htm" .

It might've been one of the biggest frauds in science - if he hadn't been correct. Food for thought.