The number of electrons in a copper penny is approximately 10x 10^23. How large would the force be on an object if it carried this charge and were repelled by an equal charge 1 meter away?

Question

anonymous · Answer

I got quite confused if I should be stripping the copper penny into infinitesimal length and charges within length or treat it as it is and solve the size of the force...

anonymous · Answer

$$F = k_0 {q_1 q_2 \over r^2}$$where q_1 and q_2 are the charge of the penny, and r^2 is the distance between the two charges. Remember that once electron has a charge of 1.609e-19 coulombs.

anonymous · Answer

I would treat the penny as a point charge, which uses the above equation.

anonymous · Answer

oh okay cool. I was going through the pain of slicing it into infinitesimal pieces because I thought I shouldn't be treating it as a particle, and I quite forgot to multiply it with 1.609E-19 too that's why I was getting my answer wrong. Thanks!