Question

question 8 of 25
you replace a 200 w lamp with a more efficient 55 w led lamp. if you leave your lights on 24 hours a day, how much energy are you saving each day by replacing this bulb?
a. 21,225,000 j
b. 17,280,000 j
c. 12,528,000 j
d. 4,752,000 j

Explanation:

Step1: Calculate energy consumption of 200 W lamp

The formula for energy $E = P\times t$. Power of 200 - W lamp $P_1=200\ W$, time $t = 24\ h=24\times3600\ s$. So $E_1=P_1\times t=200\times24\times3600\ J$.

Step2: Calculate energy consumption of 55 W lamp

Power of 55 - W lamp $P_2 = 55\ W$, time $t = 24\ h = 24\times3600\ s$. So $E_2=P_2\times t=55\times24\times3600\ J$.

Step3: Calculate energy saved

Energy saved $\Delta E=E_1 - E_2=(200 - 55)\times24\times3600\ J=145\times24\times3600\ J = 12528000\ J$.

Answer:

C. 12,528,000 J