(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

Basically I am given an image showing a test charge tied to a string where there is the ball is stationary. I need to use the fact that there is no net force on the ball to derive an equation for the electrostatic force in terms of g, the angle, and the mass of the ball. Unfortunately I am stuck. :(

2. Relevant equations

3. The attempt at a solution

Well I know that the vertical portion of [tex]F_{T}[/tex] is equal in magnitude to mg, and the horizontal portion of [tex]F_{T}[/tex] is equal in magnitude to the electromagnetic force. But I don't see how to tie it together to derive an equation.

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# Homework Help: Deriving equation for electrostatic force.

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