1. Sep 26, 2009

Daysi

We know that the negative charge on the electron and the positive charge on the proton are equal. Suppose, however, that these magnitudes differ from each other by 0.00007%. With what force would two copper pennies, placed 1.2 m apart, repel each other? Assume that each coin contains 3 multiplied by 10^22 copper atoms. (Hint: A neutral copper atom contains 29 protons and 29 electrons.)

(From your answer, it should be obvious that the magnitude of the charge on a proton and the charge on an electron cannot possibly differ by as much as the given percentage.)

2. Sep 26, 2009

rl.bhat

Hi Daysi, welcome to PF.
What are the relevant equations you can use in the problem?

3. Sep 26, 2009

Daysi

ahh sorry. haven't read the rules yet.
I'm sure we can use Coulomb's law.
F=KQq/r²

4. Sep 26, 2009

rl.bhat

Your relevant equation is correct.What are the different forces acting on one pennies by the other?

5. Sep 26, 2009

Daysi

Repulsive force and attractive force? and the repulsive one is slightly larger?

6. Sep 29, 2009

Daysi

and q=29e?
I don't know how to do the rest...