An alarm clock is plugged into a 120 volt outlet and has a resistance of 15,000 ohms. How much power does it use?

The power used is 0.96 watts.

Explanation:

Recall the formula for electric power (P) as the product of the voltage applied  times the circulating current:

and recall as well that the circulating current can be obtained via Ohm's Law as the quotient of the voltage applied divided the resistance:

Then we can re-write the power expression as:

which in our case becomes:

find the surface area of the sphere to the nearest square unit. use a calculator.

a. 254 in.2

b. 64 in.2

c. 127 in.2

d. 1,018 in.2