I've been stuck on this relatively simple question for over an hour, can't get the right answer. I think my fundamental understanding of the units involved is flawed, I would really appreciate any kind of clarification as to what I'm doing... okay here goes.(adsbygoogle = window.adsbygoogle || []).push({});

I'm given that three charges are at the vertices of an equilateral triangle, with side lengths of 0.8 meters. The charges are given in units of (mu)C, which I understand to be microCoulombs, is that correct? Two of the charges, mainly the left and uppermost ones, are positive; they are +2.4 microCoulombs and +6.8 microCoulombs, respectively. The third charge, on the right, is negative, a -4.2 microCoulombs. I am asked to calculate the electric field at the point of the leftmost (+2.4) charge, due to the other two charges. The answer is expected in vector format, and in kN/C (killoNewtons per Coulomb?).

This shouldn't be hard, using the equation for electric field,

Ke*(Q/r^2). What I do every time is:

convert the microCoulombs to Coulombs by dividing by 1.6 * 10^6.

So I have 6.8 * 10 ^ -6 Couloumbs, -4.9 * 10 ^ - 6 Couloumbs, and the third point doesn't matter, since that's where I'm calculating electric field at. Basically then [ Ke * (6.8 * 10 ^ -6 C) / (0.8 m) ^ 2 ], that's the magnitude, and I divide it into x and y components by multiplying by cos(60) and sin(60) respectively. x should be negative (it extends outward from positive charge to the left on the x-axis) and y is also negative (it extends outward from positive charge down on the y-axis).

For the other one, it's [ Ke * (-4.9 * 10 ^ -6 C) / (0.8 m)^2]. It lays directly horizontal to the point in question, so no y-component, it's all x-component and it's positive since the negative charge produces a field directed toward itself.

Add components, which should produce and answer in C/N, then divide by 1000 to get kN/C.

Seems simple, what am I doing wrong? Sorry if the description is too in-depth or not enough so. Please help me someone!!!!!!!!!

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# Homework Help: Stuck on electric field question

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