# Magnitude and Direction of Electric Field

1. Sep 14, 2009

### bwilhelm

1. The problem statement, all variables and given/known data
Two point charges are placed on the y-axis. One is +3.0 C and located at position (0, 2 m), the other is -2.0 C and located at the origin. Use the diagram to find the magnitude and direction of the electric field and the force on a +1.0 x 10-9 C test charge placed in the following locations.
a. (0, 1.0 m)
b. (0, -2.0 m)
c. (1.0m, 0)

2. Relevant equations

E= kq/(r^2)

3. The attempt at a solution
So for part a:
F= (K(3x10^-6)/(1^2) + K(2x10-6)/(1^2))
E= F/(test charge)

Same for part b, but the radius is different.
My question is how do I get part C?
I calculated the force between the -2uc charge and point C, but how do I get the force between the +3uc charge and point C?

Do I need to find the angle?
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

#### Attached Files:

• ###### diagram.jpg
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2. Sep 14, 2009

### rl.bhat

Find the distance between points ( 0, 2) and (1,0).
Find field at (1,0) due to + 3μC and - 2μC.
Resolve the field due to +3μC into x and y components.
Find the net x component and find the resultant with y component.

3. Sep 15, 2009

### bwilhelm

Thank you for the reply, i'll try this out tomorrow.