How many extra electrons does an object with a charge of -21mC have?

Answer 1

Charges are quantized. This means that they have quantities. Therefore, q=ne. q is the the charge, n is the number of electrons you are trying to find, and e is the charge on the electron. Remember that your given charge is in micro coulombs, and you'll have to turn that into coulombs. -21x10^-6 c/1.6X10^-19c =n, this will give you the number of extra electrons. hope this helps!

Answer 2

An object with a charge of -21mC has an excess of 21 million electrons. This is because each electron carries a charge of -1.6 x 10^-19 coulombs. So, 21mC divided by -1.6 x 10^-19 C ≈ 21 x 10^(-3) / 1.6 x 10^(-19) ≈ 1.31 x 10^(16) electrons.