# Electric field question

1. Jun 2, 2005

### Jchem

a) calculate the electric field at a point A(5,4) m, in both magnitude and direction due to two electric charges q1 = 2.0 x 10^-9 C and q2 = -6.0 x 10^-9 C located at (0,4) m and (3,4) m respectively in the xy plane.

b) find the same components at the origin due to the same charges.

----------------------------------------------------------------

anyone want to point me in the right direction?

or let me know of a website where I can learn about these problems.. I know how to deal with 1 charge.. but have no idea with this question.

thanks for any help.

2. Jun 2, 2005

### OlderDan

If you know how to deal with one charge, and you know how to add vectors, you can deal with two charges. Each charge produces its own electric field at each point in space. All you have to do is add the two field contributions at each point to find the net field. Just remember the electric field is a vector pointing directly away from a positive charge and toward a negative charge.

3. Jun 2, 2005

### Dr.Brain

As told by OlderDan , you just need to be familiar with vectors and how to take vector components . Since the sign for a charge at (5,4) is not told about , you can always take it as positive. Other way around , you can first calculate the field due to both and then take components in two directions and apply Parallelogram Law or you can apply it directly.Look for symmetrical situations, go for the easiest you find.