Register to reply

Excess electrons and net charge

by eku_girl83
Tags: charge, electrons, excess
Share this thread:
eku_girl83
#1
Jan14-04, 05:42 PM
P: 90
In my college physics class, we are working on electrostatics. Our homework problems relate to Coulomb's law, but I don't know how to manipulate it to solve them. Here are some examples:

1)Excess electrons are placed on a small lead sphere of mass 20 g so that its net charge is -2.60x10^-9 C. Find the number of excess electrons on the sphere.
2) How many excess electrons are there per lead atom? The atomic number of lead is 82, and the atomic mass is 207 g/mol.

Any help/explanations would be greatly appreciated!
Phys.Org News Partner Science news on Phys.org
New type of solar concentrator desn't block the view
Researchers demonstrate ultra low-field nuclear magnetic resonance using Earth's magnetic field
Asian inventions dominate energy storage systems
himanshu121
#2
Jan15-04, 04:42 AM
himanshu121's Avatar
P: 658
Apply Q=ne where Q is total charge and e electronics charge whereas n is the no of electrons
HallsofIvy
#3
Jan15-04, 06:46 AM
Math
Emeritus
Sci Advisor
Thanks
PF Gold
P: 39,491
Just to elaborate slightly on himanshu121's response:

(a) Do you know the charge on a single electron? If you don't, then you should look it up. I'll bet it's in your textbook. Once you know that, how many electrons would it take to make -2.60x10^-9 C?

(b) Once you know the answer to (a), you can divide it by the number of lead atoms to find the number of electrons per atom. Of course, to do that you need to know how many atoms of lead there are in 20 g of lead. How many atoms are there in 1 gram?

eku_girl83
#4
Jan15-04, 11:47 AM
P: 90
Excess electrons and net charge

Thanks you guys! I now have my problems worked correctly :)


Register to reply

Related Discussions
How to find the number of excess electrons? Introductory Physics Homework 5
Excess electrons question Introductory Physics Homework 1
Excess electrons or protons on drop. Introductory Physics Homework 3
Excess electrons on a lead sphere Introductory Physics Homework 2