# Homework Help: Work performed on a proton between two charged plates

1. Feb 4, 2010

### KidDreamer

1. The problem statement, all variables and given/known data
A set of parallel conducting plates are seperated by .05 m. When the plates are fully charged to a potential difference of 20 V, how much work would have to be performed to move a proton from the negatively charged plate to the positively charged plate?

My second question would be, is it negative work because its moving a positive charge towards the postive plate?

2. Relevant equations
V = k*q/r
We = qV
V = Ed

3. The attempt at a solution
20 * ? Im sorry i just dont understand this concept that well

2. Feb 4, 2010

### rl.bhat

Work = F*d*cosθ.
Here force on the proton is E*q away from the positive plate.
Proton is moving towards the +ve plate. So θ = 180 degrees.
With these information find W.

3. Feb 4, 2010

### KidDreamer

Wait...so I understand it being 180 degrees...but i do i need to use the protons charge as 1.6*10^-16 to find the force applied first?

4. Feb 4, 2010

### rl.bhat

Yes.
The final formula will be
W = V*q*cosθ.