Point Charges and Static Electricity Problem

[supmiller]

Hi! I am having a tough time with this question, and would just like some clarification if that's at all possible! I feel I may just be missing a key concept, however, any help is appreciated! Thanks.

Homework Statement

Point x is .25 m away from a point charge of +4.7*10^-8 C, point Y is .65 m away. What is the potential of point X with respect to point Y?

Homework Equations

Ep=(kQ1Q2)/d

Where k= 9.0*10^9
And Ep is the electric potential difference

The Attempt at a Solution

Solve Ep for each individually (Points x and y)

Point Y
Ep=(9.0*10^9)(+4.7*10^-8)/(.65)
=650.77V

Point X
Ep=(9.0*10^9)(+4.7*10^-8)/(.25)
=16581.8V

Point X-Point Y = 15930.83V

 

[anathema]

Hi! It looks like you have the right idea, but there are a few things to clarify. First, the formula you are using is for the electric potential energy, not the electric potential difference. The electric potential difference is given by the formula V=kQ/d, where V is the electric potential difference, k is the Coulomb's constant, Q is the charge of the point charge, and d is the distance from the point charge. So, for point Y, the electric potential would be V=(9.0*10^9)(4.7*10^-8)/(.65)=650.77V. However, for point X, the electric potential would be V=(9.0*10^9)(4.7*10^-8)/(.25)=16581.8V. To find the potential difference between point X and point Y, you would then subtract the two values, giving you a potential difference of 15931.03V. I hope that helps clarify things for you! Let me know if you have any other questions.