A metal sphere has a charge of +12C. What is the net charge after 2.1 x 1013 electrons have been placed on it?

2.1*10^13 electrons will have a negative charge of 2.1*10^13 e, where

e = 1.6*10^-19 C

The net charge won'r be changed much at all.

Are you sure the original charge was not 12 MICROcoulombs (uC?). Then there would be a significant change in net charge

The original charge is supposed to be 12 Microcoulombs... sorry for the confusion

To find the net charge after adding electrons to a metal sphere, you need to consider the charge of the electrons and the initial charge of the sphere.

The charge of an electron is -1.6 x 10^-19 C, while the charge of the metal sphere is given as +12 C.

First, let's calculate the total charge added by the electrons:
Total charge added = (number of electrons) * (charge per electron)
Total charge added = (2.1 x 10^13) * (-1.6 x 10^-19)

To find the new net charge, we need to add the total charge added by the electrons to the initial charge of the sphere:
Net charge = initial charge + total charge added

Substituting the values:
Net charge = +12 C + (2.1 x 10^13) * (-1.6 x 10^-19)

Now, let's calculate the result:

Net charge = 12 C + (-3.36 x 10^-6) C

To simplify the expression:
Net charge = 12 C - 3.36 x 10^-6 C

Therefore, the net charge after 2.1 x 10^13 electrons have been placed on the metal sphere is approximately 11.99999664 Coulombs or 1.2 x 10^1 C (rounded to two decimal places).