(adsbygoogle = window.adsbygoogle || []).push({}); Stuck on two electric field questions....

Hi guys,

I have these two questions which I am unable to answer.

This is the first one:

Calculate the magnitude of the electric field at one corner of a square 1.26 m on a side if the other three corners are occupied by 2.80×10-6 C charges .

Hint: Draw the diagonal through the square from the lower left with one of the 3 charges to the upper right with the point where the electric field is wanted; the resulting field due to the 2 other source charges on either side of the diagonal points along the diagonal (why ?); calculate the magnitude for the vector sum; add this value to the field due to the charge on the lower left which also points along the diagonal (simply add the numbers).

I don't really even know how to start....(there is an example like this in my text book 'physics'by Giancoli, but it is quite different from this question)

the second one:

A positive point charge Q1 = 3.43×10-5 C is fixed at the origin of coordinates, and a negative charge Q2 = -7.27×10-6 C is fixed to the x axis at x = +1.97 m. Find the location of the place along the x axis where the electric field due to these two charges is zero.

E = kQ/r^2

I set up E = 0 = 308700/1.97^2 - 65430/1.97^2

I set it to equal zero, but obviously that is incorrect.

I think I'm getting confused because one of the charges is set at the origin, it threw me off a little bit. So I know that for the first part the "r" should not be 1.97....

Any help is appreciated.... thanks....

**Physics Forums | Science Articles, Homework Help, Discussion**

Dismiss Notice

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Homework Help: Stuck on two electric field questions

**Physics Forums | Science Articles, Homework Help, Discussion**