Attempting to find tension force with electric fields

[mfgrape123]

Homework Statement

A small conducting sphere of mass 5.0x10^-3 kg attached to a string of length 20 cm, is at rest in a uniform electric field E. There is a charge of -5.0x10^-6 coulomb on the sphere. The string makes an angle of 30° with the vertical. Calculate the tension in the string. Calculate the magnitude of the electric field.

Homework Equations

Probably have to use Fm = BIlsin° Not sure what else, though.

The Attempt at a Solution

Honestly, I have no idea where to start. We haven't really covered this in class yet, and I don't know what to Google to figure it out that way... Help, please?

 

[haruspex]

Can you draw the free body diagram? What are all the forces on the mass? What do you know about the magnitude and direction of each?

 

[mfgrape123]

Okay, I think this is the right free-body diagram. I could be wrong, though. But this is the apparatus set-up we're given.

 

[haruspex]

The OP doesn't say the field is horizontal (so doesn't provide enough info for a solution), but maybe you left that out. So your diagram looks ok. Can you write down the equilibrium equations?