# Mastering physics: The Electric Field at a Point Due to Two Point Charges

1. Mar 6, 2010

### silver421

1. The problem statement, all variables and given/known data
A point charge q1:-4.00 nC is at the point x=0.600 meters, y=0.800 meters, and a second point charge q2:+6.00 nC is at the point x=600 meters, y=0 .

a) Calculate the magnitude of the net electric field at the origin due to these two point charges.

b) What is the direction, relative to the negative x axis, of the net electric field at the origin due to these two point charges.

$$\phi$$= _________ (up from the negative x axis)

2. Relevant equations

3. The attempt at a solution
I tried calculating E1 and E2 and added them both to get E but my answers are wrong

2. Mar 6, 2010

### CompuChip

That is the correct way, as long as you take into account the fact that the electric field has a direction as well.

Can you show us how you calculated, for example, E1?

3. Mar 6, 2010

### silver421

i used the equation E=K|q|/r^2. i used these numbers K= 8.988x10^9 q= 4.00x 10^-9 nC
r= square root of: (0.600)^2 + (0.800)^2
and i got E1= 35.95

and for the angle part i have no idea how to do it!