# Simple question: Find charge given mass, electric potential difference and radius

## Homework Statement

Find the charge
find the charge:
mass : 3.6*10^-12 kg
electric potential difference: 250.4 V
parallel plates are 0.41 cm apart

Just need to know how to find charge in this case
Thanks for the help in advance!

## Homework Equations

I thought it was:
V=(kq)/r
so q= (Vr)/k
But what would the mass be there for?

## The Attempt at a Solution

q= (Vr)/k
q= (250.4*0.0041m)/(9.0*10^9)
q=1.1*10^-10

i dont know whether this is the right way of finding it

NascentOxygen
Staff Emeritus
wow22, I think you have abbreviated the details too much, and what you provided is not meaningful. Parallel plates I understand, voltage across the plates I understand. But mass....? What body is this whose mass is part of the question? And what is it is that has a radius?

It's the mass of an oil drop and im looking for the charge of it. That's basically all the info given to me, and the question isn't really given to me in a word question, it just says to find the charge of the drop with info in chart provided.

gneill
Mentor
It's the mass of an oil drop and im looking for the charge of it. That's basically all the info given to me, and the question isn't really given to me in a word question, it just says to find the charge of the drop with info in chart provided.

Why didn't you explain the setup in your first post? Without context your question is indecipherable.

What is the electric field strength between the plates?
What forces are acting on the charged droplet?

not sure ..
considering it didn't say i'm going to assume that it's stationary.