Question

A piece of purple plastic is charged with 8.51 × 106 extra electrons compared to its neutral state. what is its net electric charge (including its sign) in coulombs.

Answer 1

Each electron provides a charge of -1.602 × 10^-19 coulombs.

If there are 8.51 × 10^-6 extra electrons:

1 electron ­____________ -1.602 × 10^-19 coulombs

8.51 × 10^6 electrons___x = -1.602 × 10^-19*8.51 × 10^6/1=-1.32× 10^-12 coulombs

So the extra electrons provide a charge of 1.32× 10^-12 coulombs.

So the net charge is -1.32× 10^-12 coulombs (there are more electrons besides those extra electrons, but there are also protons, so they don’t affect the net charge – the other electrons just compensate the charge of the protons).