# Problem with electric forces

1. Jan 10, 2005

### compute_a_nerd

Hello all. I am kindof stuck on this problem. It asks: The figure below shows three point charges all posotive. If the net electric force on the center charge is zero, what is the value of y/x.
a) 4/9
b) $$\sqrt{2/3}$$
c) $$\sqrt{3/2}$$
d) 3/2
e) 9/4

This is my figuring:

$$K\frac{2q}{x^2} - K\frac{3q}{y^2} = 0$$

But how can I get an actual number without a value for q?
Thanks
Chris

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2. Jan 10, 2005

### dextercioby

You can divide the whole equation through $\frac{1}{4\pi\epsilon_{0}\epsilon_{r}}=:K$ and "q" and then try to see which numbers fit the equation left...

Daniel.