# Homework Help: Elementary Charge

1. May 1, 2005

### thomasrules

Calculating charge and force of electric repulsion

Calculate the force of electric repulsion between two small spheres placed 1m apart if each has a deficit of 1x10^8 electrons.

I tried this and only got r=1m and N=1x10^8

Thomas

Last edited: May 1, 2005
2. May 1, 2005

### Andrew Mason

Do you know the charge (in Coulombs) of the electron? Just use that in the Coulomb force equation.

AM

3. May 1, 2005

### thomasrules

so what would q be? Whats the charge on both spheres?

4. May 1, 2005

### Andrew Mason

If each has a deficit of 10^8 electrons, each has 10^8 more protons than electrons. So each has a charge of +10^8 e, where e = -1 x charge of one electron. The charge of one electron is -1.602 x 10^-19 C.

AM

5. May 1, 2005

### thomasrules

so its (1.602x10^-19)(10^8)=charge?

6. May 1, 2005

### Andrew Mason

Well, that is one of the charges. The other one is the same. Do you know how to apply Coulomb's law to find the force at a separation of one meter?

AM