Atoaster is plugged into an 120-volt outlet. if it has a resistance of 460 ohms, how much power does it use?
a. 1,800 watts
b. 3.8 watts
c. 31 watts
d. 55,000 watts
e. 340 watts

Here are a few formulas for electrical power:

 P  =  (voltage) x (current)

 P  =  (voltage)²  /  (resistance)

 P  =  (current)²  x  (resistance)

We know the voltage and the resistance, so it seems to me that
we should use the middle one.

      Power  =  (voltage)²  /  (resistance)

                 =  (120 volts)²  /  (460 ohms)

                 =  (14,400 volts²)  /  (460 ohms)

                 =  31.3 watts .

That's not much power for a toaster.  It produces about as much heat
as a small (30 watt) light bulb. 

You would not sell many toasters designed like this one, because
it would take several days to toast a slice of bread.

A toaster that has what it takes to do the job will typically use
1200 watts to 1600 watts, just like a typical blow-dryer.