Electricity and Magnetism
# Charges and Their Interactions

A nail with a mass of $17 \text{ g}$ is charged with $- 2.24 \times 10^{-13} \text{ C}.$ How many excess electrons are in the nail?

The elementary charge is $e=1.60 \times 10^{-19}\text{ C}.$

How many excess electrons are there on a tiny, spherical water drop of charge of $-4.00 \times 10^{-16}\text{ C}?$

The elementary charge is $e=1.60 \times 10^{-19}\text{ C}.$

If a current of $0.30\text{ A}$ flows for $2.50\text{ min}$ in a conducting wire, approximately how many conduction electrons pass through the wire?

The elementary charge is $e=1.60 \times 10^{-19}\text{ C}.$

Suppose there is a small (copper) coin with a mass of $25 \text{ g}.$ If we want to leave it with a charge of $+1.4 \times 10^{-7}\text{ C},$ approximately how many electrons must be removed from that metal coin?

The elementary charge is $e=1.60 \times 10^{-19}\text{ C}.$

If an average current of $0.07\text{ A}$ flows from a conducting sphere for $5\text{ sec}$ and then stops, what can we know about the sphere?

The elementary charge is $e=1.60 \times 10^{-19}\text{ C}.$