# Electrical Field

1. Jan 12, 2008

### rhodium

hi everybody,

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

A +2 C charge is 20cm to the right of a -3 charge. What is the electric field on the line excatly halfway between the two charges?

2. Relevant equations

E = kq/d^2

3. The attempt at a solution

force of attraction; therefore vector of -3 charge would be to the right and vector of 2 charge would be to the left (negative).

E= k(3)/(0.1^2) + k(-2)/(0.1^2) = 9 x 10^11

The handout answer is 4.5 x 10^12 N/C (left). Am I using the wrong equation?

2. Jan 12, 2008

### belliott4488

It's the right equation, but you're using it incorrectly.

When you say "vector of -3 charge would be to the right and vector of 2 charge would be to the left", do you mean that these are the directions of the field vectors from each of these charges? This isn't correct.

How do you determine the direction of the field, given the sign of the charge?

3. Jan 14, 2008

### rhodium

thank you so much!

salam

Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook