I'm trying to find electric potential.

[+Jace090+]

Homework Statement

There is a 4 cm by 3 cm rectangle with 2.0 nC charges at three corners. I'm trying to find the electric potential of the last corner in V.

Homework Equations

U=(kQq)/r I think
V=(kq)/r I think

The Attempt at a Solution

I found the U's between the know corners but i don't know where to go from there.

 

[Noctisdark]

Hello Jace,
You add them up :) !

 

[+Jace090+]

In this situation? I don't know if I adequately described it.

 

[+Jace090+]

I found the U's of the sides with dimensions.

 

[Noctisdark]

Aww, sorry for the mistake, There is no electric potential in the 4th corner, because there is no charge there, However you can calculate the voltage there (V) .

 

[+Jace090+]

oh... thank you.

 

[+Jace090+]

Apparently there is because I typed in 0 and the program said I was wrong.

 

[+Jace090+]

It wants the V for that point, so where would I go from having the U's of those adjacent to it?

 

[Noctisdark]

Then, by electric potential he mean V (voltage), no charge means no electric potential energy (by intuition and the formula insists on that), however, calculate the voltage out there :)

 

[+Jace090+]

How would i go from U to V? What U would I use?

 

[Noctisdark]

You can't go from U to V, because there'there's no charge out there, but one thing you can do is use V = kQ/R
[Edit: you can't because you'll be dividing by zero, moreover U = 0]

 

[+Jace090+]

What Q and what R?Would i use the average?

 

[Noctisdark]

R is the distance to the 4th coner, Q is the charge at each corner.
Calculate the potential due to each charge and sum them up !