Question

The current in an electric hair dryer is 10

Answer 1

First let's convert the time in seconds:
$\Delta t= 5 min= 5 min \cdot (60 s/min)= 300 s$

The current is defined as the quantity of charge flowing through a certain section of a circuit per unit of time:
$I= \frac{Q}{\Delta t}$
Using I=10 A, and $\Delta t=300 s$, we can find the amount of charge flown through the hair dryer in this time:
$Q=I \Delta t=(10 A)(300 s)=3000 C$

The charge of a single electron is $q=1.6 \cdot 10^{-19} C$, so the number of electrons flown through the hair dryer is the total charge divided by the charge of a single electron:
$N= \frac{Q}{q}= \frac{3000 C}{1.6 \cdot 10^{-19} C} =1.88 \cdot 10^{22}$