Question

An 11.0-W energy-efficient fluorescent lightbulb is designed to produce the same illumination as a conventional 40.0-W incandescent lightbulb. Assuming a cost of $0.111/kWh for energy from the electric company, how much money does the user of the energy-efficient bulb save during 220 h of use?

Answer 1

`Savings = $0.709`

Step-by-step explanation:

Energy consumed by 11 W energy efficient fluorescent bulb is given as

`E = Power * time`

now we can say

`E = 11 * 220h`

`E = 2.42 kWh`

now total cost of the energy used is given as

`Amount = 2.42 * $0.111`

`Amount = $0.268`

Now for conventional 40 W bulb we can say

`E = Power * time`

now we can say

`E = 40.0 * 220h`

`E = 8.8 kWh`

now total cost of the energy used is given as

`Amount = 8.8 * $0.111`

`Amount = $0.977`

So total money saving is given as

`Savings = $0.977 - $0.268`

`Savings = $0.709`