- #1

CKaiL

- 38

- 1

## Homework Statement

## Homework Equations

## The Attempt at a Solution

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The electric field at the origin O, due to charges Q, q1 and q2, is equal to zero

Hence , EQ = Eq1

q = cos30 x 300 x10^-9/4 * 1.8^2 = 210 x10^-9 C

So I am able to find out that q = 210 x 10^-9 C and that mean that B and C cannot be the answer which left me with A and D.

How do I check if it is a positive charge or negative charge?

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