# Calculating Electric Field due to two point charges.

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1. Aug 11, 2015

### Mnemonic

1. The problem statement, all variables and given/known data
Two points charges.

q1=2.4e-6 C is located at (0,0)

q2=-5.7e-6 C is located at (3,0)

I must calculate the magnitude of the Electric field at (0,0)

2. Relevant equations
E=kq/r^2 ; k=9e9

3. The attempt at a solution
The electric field at (0,0) due to q2=9e9x(-5.7e-6)/3^2 = -5700N/C

Next would be to add the electric field at (0,0) due to q1.
However, I don't know how to calculate the field as distance is r=0 which doesn't work with the formula.

How do I calculate the electric field due to a point charge AT the point charge?

Last edited: Aug 11, 2015
2. Aug 11, 2015

### Orodruin

Staff Emeritus
You don't. Please quote the problem exactly as stated and not your interpretation of it.

3. Aug 11, 2015

### Mnemonic

"Consider a system where a charge -5.7-μC is located at x = 3.0-m, y = 0.0-m and another charge +2.4-μC is located at x = 0.0-m, y=0.0-m. Find the magnitude of the electric field at x = 0.0-m, y = 0.0m. "

4. Aug 11, 2015

### Orodruin

Staff Emeritus
This is very likely a misprint in the problem statement. It is likely that one of the values of the positions is wrong or, if part of a bigger problem, the field at (0,0) from q2 is what is intended.

5. Aug 11, 2015

### Mnemonic

The next part is :In what direction is this electric field orientated, measured in the normal way (anti-clockwise from the x-axis, which is pointing to the right in the above figure)?

I tried just the field at (0,0) from q2 at got the wrong answer :( Will try and contact my lecturer

To put it simply is it impossible to determine the electric field from a point charge at the point charge?

6. Aug 11, 2015

### SammyS

Staff Emeritus
The answer to this is: NO !