Electrical field at the center of a hemisphere

[silversound]

Charge is distributed uniformly on the surface of a hemisphere. Find the electrical field at the center of the sphere due to that.

Can anyone help me?pls ^___^

 

[berkeman]

What equation should you use for calculating the electric field resulting from a distribution of charge?

 

[robphy]

As a preliminary step, can you determine the direction of the electric field ?