Insulator and electron problem

[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

 

[Defennder]

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

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

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

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.

 

[baba89]

I would say that the correct answer to the first question is c. 10^11 electrons. This is because electrons are negatively charged particles and a negative charge of 160 NC would indicate an excess of 160 coulombs of electrons. Since each electron has a charge of 1.6 x 10^-19 coulombs, dividing 160 by 1.6 x 10^-19 would give you 10^11 electrons.

For the second question, the answer would be d. either a positive or negative charge. This is because when the negatively charged insulator is brought near the two uncharged metal spheres, it will induce a charge on the spheres. This means that one sphere will have an excess of electrons (negative charge) and the other will have a deficiency of electrons (positive charge). When the spheres are separated, the sphere that had an excess of electrons will have a negative charge and the other sphere will have a positive charge. The exact amount of charge on each sphere will depend on the distance between them and the strength of the charge on the insulator. Therefore, the answer is not definite and could be either positive or negative.