# Potential difference between the plates?

#### dark_angeL23

1. Homework Statement

A small electrically charged object is suspended by a thread between the vertical plates of a parallel-plate capacitor. The acceleration of gravity is 9.8 m/s^2.
What is the potential difference between the plates? Answer in units of kV.

Given: tetha = 14 degrees
mass of the object = 152 mg
q = 15 nC
distance between the two plates = 5.6 cm

2. Homework Equations

I used the following:

delta V = U/Q
U = F x d

3. The Attempt at a Solution

I got U = 0.0000834176 Joules
and I got V = 5561.1733333 V
which is V = 5.561173333 kV

but it's wrong.

Related Introductory Physics Homework Help News on Phys.org

#### LowlyPion

Homework Helper
1. Homework Statement

A small electrically charged object is suspended by a thread between the vertical plates of a parallel-plate capacitor. The acceleration of gravity is 9.8 m/s^2.
What is the potential difference between the plates? Answer in units of kV.

Given: tetha = 14 degrees
mass of the object = 152 mg
q = 15 nC
distance between the two plates = 5.6 cm

I got U = 0.0000834176 Joules
and I got V = 5561.1733333 V
which is V = 5.561173333 kV

but it's wrong.
Welcome to PF.

How did you resolve the force of gravity and the electrostatic force to determine your E field?

#### dark_angeL23

Thank you.

I got it.
It took forever to finally get a reply from someone, so I asked someone else.

What I did was Tcos(tetha) = (152x10^-6)(9.8)
then, F=Tsin(tetha)

Then I used, E=F/q
Then I used, V=Ed, V/1000 (conversion from V to kV)

My final answer is V = 1.386556241 kV

And it's correct!

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