# Calculating Electric Field due to two point charges.

## Homework Statement

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)

E=kq/r^2 ; k=9e9

## 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:

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

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

"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. "

Orodruin
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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.

Mnemonic
This is very likely a misprint in the problem. 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.

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?

SammyS
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