A negatively charged balloon has 3.5 microcoulombs of charge. How many excess electrons are on the balloon?

To find the number of excess electrons on the balloon, we can use the relationship between charge and the charge of a single electron. The charge of one electron is approximately 1.6 x 10^-19 coulombs.

The total charge on the balloon is given as 3.5 microcoulombs, which is equivalent to 3.5 x 10^-6 coulombs.

To find the number of excess electrons, we can use the formula:

Number of electrons = Total charge / Charge of one electron

Substituting the values:

Number of electrons = (3.5 x 10^-6 C) / (1.6 x 10^-19 C/electron)

This calculation yields:

Number of electrons ≈ 2.1875 x 10¹³ electrons

Therefore, the negatively charged balloon has approximately 2.19 x 10¹³ excess electrons.