Millikan's oil drop experiment - help

[jaderberg]

Im doing millikan's oil drop experiment as my A level physics coursework to eventually calculate the electronic charge. I am fine with all the theory but what I am really struggling with is the actual practical experiment.

I have seen the oil drops a lot and have managed to manipulate them using a voltage however now when I've come back to the experiment after the weekend i can't see anything and if i do see something its just a really faint cloud of oil drops where i can't pick out a single one to analyse. Why is it so temperamental?

Also i got some initial results for oil drops (which came out to be about 2micrometers radius) under a voltage of around 200v but the charge was far too high (approximate to 100-200 electrons). I hooked up the apparatus to a higher voltage and tried to take some results (at about 1000-2000V) but didnt get much...are all my oil drops too highly charged? I really want to isolate and analyse some which only have a few electrons on them but this seems impossible. Would removing the rubber end of the atomiser stop the oil drops from being so highly charged?

Any help would be really appreciated as well as any practical tips for the experiment (i only have 4 hours left!)

Thanks

 

[member 553083]

in advance!One of the most important practical tips is to make sure that you have a good vacuum on your apparatus. This will help ensure that the oil drops remain suspended in the air and are easier to observe. Additionally, it's important to ensure that your voltage is regulated and consistent throughout the experiment, as this will help ensure that you don't end up with overly charged oil drops. Finally, if you're having trouble finding individual oil drops, try using a light source to illuminate them and make them easier to see. You can also reduce the background lighting in the room to make them easier to spot.