# Charge surrounded by charged conducting sphere

1. May 2, 2013

### iriver4

A spherical conducting shell with charge total q surrounds a charge –2q at the center of the shell. The
charges on the inner and outer surfaces of the shell are respectively

I know that if the conducting sphere has no charge the inner and outer charges would be +2q, and -2q respectively but how does q play in this problem ?

2. May 2, 2013

### SammyS

Staff Emeritus
Do you know how to explain the case:
if the conducting sphere has no charge the inner and outer charges would be +2q, and -2q respectively​
?

3. May 2, 2013

### iriver4

Sorry this is another scenario where the conducting sphere has no charge. I want to know what happens if the conducting sphere has a charge of q. How does that affect the inner and outer charges ?

4. May 2, 2013

### SammyS

Staff Emeritus
In order to explain the case:
if the conducting sphere has a charge of q. How does that affect the inner and outer charges ?​
I need to know if you understand the reasoning involved in the case where the sphere is uncharged.

5. May 2, 2013

### iriver4

Because the positive charge would induce a negative charge on the inner surface of the shell and the outer shell would have a positive induced charged. Thats how it was explained to me

6. May 2, 2013

### SammyS

Staff Emeritus
Do you know Gauss's Law? Using it tells us that charge on the inner surface of the conducting shell must be equal in magnitude, and opposite in sign to the charge at the center.

7. May 6, 2013

### iriver4

So then the charge at the inner circle would be +2q and since the outer shell has a charge of q the charge outside would be equal and opposite giving us -q. Right ? Sorry I took so long have 4 finals to study for =/

8. May 6, 2013

### SammyS

Staff Emeritus
Yes, that is correct.

9. May 6, 2013

Thank you