Static Electricity and Number of Electrons

[Nicolaus]

Homework Statement

When you rub a gold sphere with rabbit's fur, the gold takes on a negative charge (and the rabbit fur positive). Suppose the gold sphere has a mass of 190.0 g and it obtains a net charge of 0.540 μC. Calculate the ratio of the number of electrons added to the gold sphere to the number originally there. (Assume the gold sphere is completely neutral before the fur is applied.)

Homework Equations

The Attempt at a Solution

.190kg(9.11e^-31kg) = # electrons before
5.4e^-5C / (1.602e^-19) = electrons added

Then divide electrons added by electrons when neutral.
What am I doing wrong?

 

[gneill]

Homework Statement

When you rub a gold sphere with rabbit's fur, the gold takes on a negative charge (and the rabbit fur positive). Suppose the gold sphere has a mass of 190.0 g and it obtains a net charge of 0.540 μC. Calculate the ratio of the number of electrons added to the gold sphere to the number originally there. (Assume the gold sphere is completely neutral before the fur is applied.)

Homework Equations

The Attempt at a Solution

.190kg(9.11e^-31kg) = # electrons before
5.4e^-5C / (1.602e^-19) = electrons added

Then divide electrons added by electrons when neutral.
What am I doing wrong?

Think again about the number of electrons originally present in the sphere of gold. How many atoms of gold are present? How many electrons per atom?

 

[Nicolaus]

Ah, got this.
Thanks