Electric potential in relation to electric field problem

[gallib]

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

The electric potential in a region of uniform electric field is -1000 V at x = -0.900 m and + 1400 V at x = + 2.00 m. What is E_{x} ?


2. Relevant equations

e=kq1q1/r^2
v= integral of E dot ds
v=ed

3. The attempt at a solution

i am thinking i will use the equation V=Ed, so I would use V=-1000 and d equal to -.9m
then i have no idea what to do from there, any help is appreciated. thank you

[dynamicsolo]

i am thinking i will use the equation V=Ed, so I would use V=-1000 and d equal to -.9m...

This is the right direction. For a potential which only changes along one dimension, you can write E = -dV/dx ; that is, the magnitude of the field is the slope of the potential function and the direction of the field runs from higher to lower potential. (This is basically where V = Ed comes from, for the case of a uniform field.)

BTW, in that formula, d is the separation between the two points over which the potential change is measured, not a position.

So you have two values of the electric potential at two values of x. What is the slope of this (linear) function? What is the direction of the electric field?