duggielanger
- 17
- 0
Homework Statement
Two parallel plates are placed 0.10 m apart with one vertically above the
other and their edges aligned. The potential difference of the upper plate is
100 kV relative to the lower plate. What charge must a spherical raindrop of
diameter 1.0 mm carry if it remains suspended between the plates? Assume
that the electric field between the plates is uniform and give your answer in
units of the charge on an electron. (The density of water is 1000 kg m
−3
.)
Homework Equations
F=mg
v=0.75r^3d
and my be Eel=qV
The Attempt at a Solution
I first found the mass of the raindrop. And first i need to find the radius
So 1.0mm/1000=0.001 m and I want the radius so 0.001m/2=0.0005 m
Next I need to find the volume of the raindrop
v=0.75x3.14x0.01m
=2.945243113 ×10-10 m3
=2.945243113 ×10-10 m3 x 1000kg m^-3= 2.9x10^-7 kg
So we now have a mass.
Now the raindrop will have work done by gravity
F=mg
F=2.9x10^-7kg x 9.81 m s^-2= 2.9 x10^-6 kg m s^-2 or N
So I have downward force of 2.9 x 10^-6 N
Now its the next step I can't figure , I think I need to find upward force on the raindrop by finding the charge . But can't get my head around it