The electrical power of the hair dryer is equal to its voltage difference multiplied by the current:
[tex]P=VI[/tex]
In our problem, the power is P=1100 W and the voltage is V=120 V, so the current flowing in the hair dryer is
[tex]I= \frac{P}{V} = \frac{1100 W}{120 V}=9.17 A [/tex]
