# Insulator and electron problem

1. Sep 8, 2008

### Kathi201

1. If an object is determined to have a negative charge of 160 NC, you can conclude that the object has an excess of
a. 10^ 9 electrons
b. 10^10 electrons
c. 10^11 electrons
d. 10^12 electrons
e. 10^13 electrons

I came up with c. 10^11 electrons by taking 160E-9C/1.6E-19C = 10^11. I just used numbers that I found so I'm not sure if this is right and if it is I don't understand the reasoning as to why it is correct. Any help would be appreciated

I also have one more question.

If you bring a negatively charged insulator near two uncharged matallic spheres that are in contact and then separate the spheres, the sphere on the right will have
a. no net charge
b. a positive charge
c. a negative charge
d. either a positive or negative charge
e. none of the above

2. Sep 8, 2008

### Defennder

Re: Electrons

A small careless mistake here. You should have 10x10^11 which is 10^12.

Is there a picture of this? The question asks for "the sphere on the right", and I'm assuming that the setup isn't symmetrical to begin with.