How Do You Calculate the Electric Potential Difference Between Two Points?

[Fusilli_Jerry89]

Homework Statement

Point X is 0.25m away from a point charge of +4.7 E -8 C, point Y is 0.65m away. What is the potential of point X with respect to point Y?

Homework Equations

delta Ep=delta Ek
V=delta Ep/Q
delta Ep=QV
Ep=kQQ/d

The Attempt at a Solution

delta Ep = -Ep1
W=QV
W=kQQ(1/d-1/d)
QV=kQQ(1/.25-1/.65)
V=(9E9)(4.7E-8 C)(2.4615)
V=1041 V

I don't get one thing when it says with respect to Y, you put the distance of Y as d2 right? But then wouldn't you get a negative answer when it should be positive?

 

[Hootenanny]

delta Ep = -Ep1
W=QV
W=kQQ(1/d-1/d)
QV=kQQ(1/.25-1/.65)
V=(9E9)(4.7E-8 C)(2.4615)
V=1041 V

What you have done here is all correct, except the answer. You've just punched the numbers into your calculator wrong.

I don't get one thing when it says with respect to Y, you put the distance of Y as d2 right? But then wouldn't you get a negative answer when it should be positive?

The potential of x wrt to y means exactly what you have done there. In other words calculate the potential difference between points x and y like this; V_{xy} = V_{y}-V_{x}, which would lead to a positive answer.