Why Is Q Positive in Charge Balancing Equations?

[flyingpig]

Homework Statement

[PLAIN]http://img256.imageshack.us/img256/9025/93408370.jpg

The Attempt at a Solution

Shouldn't it be 2Q + x = -Q

x = -3Q?

My book say it is +Q

 

[betel]

+Q is correct.
What would happen to the single electrons carrying the charge if you joined the two spheres by a conducting wire?

 

[flyingpig]

+Q is correct.
What would happen to the single electrons carrying the charge if you joined the two spheres by a conducting wire?

Then why am I wrong? 2Q + x = -Q?

 

[gneill]

Don't you mean 2Q + (-Q) = x = +Q ?

After all, the total enclosed charge in a Gaussian surface surrounding both spheres would contain a net charge of +Q.