A glass rod that has been charged to + 12.0 nC touches a metal sphere. Afterward, the rod's charge is + 8.0 nC. a) What kind of charged particle was transferred between the rod and the sphere and in which direction? That is, did it move from rod to the sphere or from sphere to the rod? b) How many charged particles were transferred?

charge transferred to sphere = 12 - 8 = 4 nC

a)

The positive charge is decreased on glass rod, that means electrons must have entered the glass rod from the sphere which reduces its positive charge.

b)

charge transferred = 4 nC = 4 x 10⁻⁹ C

charge on one electron = 1.6 x 10⁻¹⁹ C

No of electrons transferred

= Total charge transferred / charge on one electron

= 4 x 10⁻⁹ / 1.6 x 10⁻¹⁹

= 2.5 x 10¹⁰.