# Homework Help: Constant Electric Field and Potential

1. Jan 31, 2009

### ganondorf29

1. The problem statement, all variables and given/known data

The figure below shows two points in an electric field. Point 1 is at (X1,Y1) = (3,4), and point 2 is at (X2,Y2) = (12,9). (The coordinates are given in meters.) The electric field is constant with a magnitude of 59.3 V/m, and is directed parallel to the +X-axis. The potential at point 1 is 1200.0 V.

2. Relevant equations

Vf-Vi = -Integral from i to f (E*ds)

3. The attempt at a solution

I set Vi=1200V
E = 59.3 N/C
and tried to solve for Vf

I found the distance by making a triangle connecting the two points to be the sqrt(106) and the angle formed to be 29deg. I took the cos(29) and brought that out of the integral(Im not sure if thats right, but I saw my book take the cosine of the angle so I did too).

Vf-1200 = -59.3*cos(29)*integral(from i to f) of (ds)

I solved for Vf and got 1148 V, but thats wrong. Any suggestions
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

2. Jan 31, 2009

### gabbagabbahey

Looks like you just plugged the numbers in wrong. I assume that you recognized $$\int_i^fds=\sqrt{106}$$?