Question

A hair dryer with a resistance of 9.6 ohms operates at 120 volts for 2.5 minutes. The total electrical energy used by the dryer during this time interval is

Answer 1

`2.25\cdot 10^5 J`

Step-by-step explanation:

First of all, we have to find the power used by the hair dryer, which is given by

`P=(V^2)/(R)`

where

V = 120 V is the voltage

`R=9.6 \Omega` is the resistance of the hair dryer

Substituting,

`P=((120 V)^2)/(9.6 \Omega)=1500 W`

Now we can find the total electrical energy used, given by

`E=Pt`

where P is the power and

t = 2.5 min = 150 s is the time

Substituting,

`E=(1500 W)(150 s)=2.25\cdot 10^5 J`