What is the excess charge on the surface of the earth?

[gallib]

Homework Statement

The Earth has a vertical electric field at the surface, pointing down, that averages 117 N/C. This field is maintained by various atmospheric processes, including lightning. What is the excess charge on the surface of the earth?

Homework Equations

E=ke*Q/r^2 Q=Er^2/ke

The Attempt at a Solution

I attempted to plug in E = 117, r= radius of the earch, and ke= 8.99*10^9 into the equation to find Q, but this answer was wrong. Any ideas, thanks.

 

[hectoronevu]

Why don't you use the formula for Electric flux? The Net electric flux through surface is basically Electric field * (4pi*(radius of Earth ^ 2)) = excess charge / permittivity constant.

 

[gallib]

Ah..thank you.

 

[hectoronevu]

Yeah, permittivity constant is 8.85*10^-12.