Question

What is the net electron charge in a penny with a magnitude charge of q?

Answer 1

Usually penny is made up up of copper.
One copper atom contains 29 electrons and 29 protons.
Atomic mass of copper is 63.5 g
Avogadro number =6.02×10^23
Let charge of electron is q
Let us take mass of copper penny is 1 g
Net electron charge = no of electrons x charge of electron x total no of atoms in 1g of copper penny

Total no of atoms in 1g of copper penny
=( (mass (1g) / atomic mass) x Avagadro no
( 1/63.5) * 6.02×10^23

Net electron charge = no of electrons x charge of electron x total no of atoms in 1g of copper penny
= 29 x ( 1/63.5) * 6.02×10^23 x q