A plastic rod that has been charged to -15.0 nC touches a metal sphere. Afterward, the rod’s charge is -10.0 nC.

a. What kind of charged particle was transferred between the rod and the sphere, and in which direction?

b. How many were charged particles transferred?

(a) The charge of a plastic rod decreases from −15.0 nC to −10.0 nC. That is, −5.0 nC charge has been removed from the plastic. Because it is the negatively charged electrons that are transferred, −5.0 nC has been added to the metal sphere.

(b) Because each electron has a charge of 1.60 x 10^-19 C and a charge of 5.0 nC was transferred, the number of electrons transferred from the plastic rod to the metal sphere is

\(\frac{5.0*10^{-9} C}{1.60*10^{-19} C} =3.1*10^{10}\)