# Electric Force Field Tension

1. Jan 31, 2010

### Octoshark

1. The problem statement, all variables and given/known data

The electric field between the plates of a parallel-plate capacitor is horizontal, uniform and has a magnitude E. A small object with a charge of -2.60 µC is attached to the string. Assume that the tension in the string is 0.350 N, and the angle it makes with the vertical is 10°

What is the magnitude of the electric field?
What is the mass of the object?

2. Relevant equations

E=Tsin(theta)/q

3. The attempt at a solution

E = (.350)(.1736)/-2.60x10^-6 = 23375 N/C

So I got this, but how does it help me find the mass of the object? Please forgive me if it is simple but I am refreshing on physics as the semester just started last week ;)

2. Jan 31, 2010

### Winzer

Hello octoshark.
I agree with you on the first question.

For the second, what forces are acting vertically?

3. Jan 31, 2010

### Octoshark

-PROBLEM SOLVED-

I didn't realize it was as simple as T=mg/cos(theta) from the way my teacher worded it, it didn't make sense