- #1

swede5670

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## Homework Statement

I need some help solving this question, it is the last one I have to do and I'm not sure how to solve it.

A point charge (m = 1.0 g) at the end of an insulating string of length 53 cm is observed to be in equilibrium in a uniform horizontal electric field of 9000 N/C with the charge 1.0 cm above the lowest (vertical) position. If the field points to the right determine the magnitude and sign of the point charge.

Find Magnitude in C:

## Homework Equations

T*cosTheta = mg

T*sinTheta = F(elec) = qE

## The Attempt at a Solution

I found this question on a thread from a while ago but I'm not sure entirely what it is saying. Since I have those equations I need to solve for T in the first one to insert it in the second

T*cosTheta = mg

T=mg / Cos(theta)

When I plug that into the second equation

T*sinTheta = F(elec) = qE

(mg/cosineTheta) * sineTheta = qE = F(elec)

My question is, do I need all three parts of this last equation? Or can I simplify it to this:

(mg/cosineTheta) * sineTheta = qE

Even if I do this, how do I figure out the angle?

And in this case what does E represent?