Question

How many kW-hr are used when one 100W light bulbs is used for 2 hours?

Answer 1

0.2 kW-hr

Explanation:

First, we are going to transform 100W in kW. We can use a rule of three in which we know that 1000W is equivalent to 1 kW, then how many kW are equivalent to 100W. This is:

1000W ------------- 1 kW

100W -------------- X

Where X is the the number of kW that are equivalent to 100W. Solving for X, we get:

`X=(100W * 1kW)/(1000W) =0.1kW`

Then, for calculate the number of kW-hr we need to multiplicate the number of kW with the number of hours, This is:

0.1 kW * 2 hours = 0.2 kW-hr

Finally, when one 100W light bulbs is used for 2 hours, it used 0.2 kW-hr