How Does Adding Electrons Affect the Net Charge of a Metal Sphere?

[sheri1987]

Homework Statement

A metal sphere has a charge of +8.0 µC. What is the net charge after 9.00 *10^13 electrons have been placed on it?

Homework Equations

q=Ne where q is the charge, N is the number of electrons, and e is given as 1.6*10^-19

The Attempt at a Solution

Well the problem gives us a charge, q, and the N, number of electrons, so I figure somehow I need to use this equation. I am not sure where to start though, could someone get me started? Thanks!

 

[Kurdt]

The electrons have a negative charge. That charge will be given by the product of the number of electrons and the charge of the electrons. Since the sphere starts with a positive charge the net charge will be the initial positive charge plus whatever charge all the electrons have. Be careful with signs here.

 

[sheri1987]

I'm still having trouble...what number needs to be negative?

 

[Kurdt]

Electrons have a negative charge.