A smart phone charger delivers charge to the phone, in the form of electrons, at rate of - 0.75 C/s. How many electrons are delivered to the phone during 45 min of charging?

Answer: 1.26 * 10^22 electrons

Explanation: In order to explain this problem we have to use the following relationship:

the charger delivers - 0.75C/s; during 45 min it will deliver

-0.75*45*60=2025C

so considering that the electron charge is - 1.6 * 10^-19 C

We have:

-2025 C/-1.6 * 10^-19 C 1.26 * 10^22 electrons