# Three negative point charges lie along a line

1. Feb 2, 2012

### kirby2

Three negative point charges lie along a line as shown in the figure.

figure: http://tinyurl.com/7xppvc8

Find the magnitude and direction of the electric field this combination of charges produces at point , which lies 6.00 from the charge measured perpendicular to the line connecting the three charges.

ATTEMPT:

i think the magnitude is to the right, away from the -2.00 uC charge. can someone verify this? i am currently trying to find the magnitude, but i will post it when finished.

Last edited: Feb 2, 2012
2. Feb 2, 2012

### mathman44

Electric fields for negative charges tend to point "towards" the negative charge. So I would not agree that the field points to the right at the point P.

To find the total magnitude/direction, find the magnitude of the field produced by each charge at the point P, and use the fact that the direction of ONE field due to ONE negative charge will point directly from the point P to the negative charge.

3. Feb 2, 2012

### kirby2

thank you. my mistake. for the magnitude i got 1.04E7 N/C. i found the x components of E for the charges. I know that there is no net E in the Y direction. then i added those x components up. is this correct? (1.04E7 N/C)

4. Feb 2, 2012

### mathman44

I haven't done the calculation... but that seems fine.