Calculating Charge of Oil Drop in Electric Field

AI Thread Summary
The discussion revolves around calculating the charge of an oil drop suspended in an electric field during an experiment. A 20 mg oil drop is held between parallel plates with a 300 V potential difference and a separation of 1.5 cm. Participants clarify that while the problem asks for the charge, the mass is necessary to balance gravitational and electrical forces. Understanding this balance is crucial for accurately computing the excess electronic charges on the drop. The conversation highlights the importance of both charge and mass in solving the problem effectively.
Physicsisfun2005
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another fun Ap phyiscs problem..short as usual:

In one run of the oil drop experiment a 20 mg drop was suspended between parallel plates 1.5 cm apart when the potential difference was 300 V. Compute the number of excess electronic charges on the drop.

is this just saying "compute the oil drop's charge" ?...if so why do i need to know the mass in this problem? ...i think i can compute it w/o that info.
 
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Yes, they are asking for the drop's charge and you need the mass because you must balance gravity and the electrical force.
 
ahhh ic...thanx
 

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