# Homework Help: Electric forces and charges

1. Oct 3, 2012

### Kiely

1. The problem statement, all variables and given/known data
Find the magnitude and direction at the midpoint of two point charges q1=20nC and q2=-40nC

2. Relevant equations
How can we answer the question if we aren't given the distance?

3. The attempt at a solution
Do I solve in terms of x for distance and use the formula F=K(q1q2)/r^2?

2. Oct 3, 2012

### Staff: Mentor

Welcome to the PF.

Are you sure that you are not given a separation distance? You would need that in order to calculate the resulting E field...

3. Oct 3, 2012

### Staff: Mentor

Magnitude and direction of what? The electric field?

Is there a diagram to accompany this problem?

Seems like that would be a key piece of information.

You could do that, but my guess is that they meant you to have the distance. Seems too odd to give you the charges but not the distance between them.

4. Oct 3, 2012

### vela

Staff Emeritus
Was there a figure that accompanied the problem? Perhaps the needed information is on there.