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A lightbulb has a power of 100 W and is used for 4 hours. A microwave has a power of 1200 W and is used for 5 minutes. How much energy is used by the lightbulb? How much energy is used by the microwave? The lightbulb has an efficiency of 1.8%. How much heat energy does the lightbulb produce in 4 hours?

Respuesta :

Gasaqui

Answer:

a. E=1440KJ

b. E=360KJ

c. E=1.8 J

Explanation:

I have the power (Watts) is expressed as Energy (Joules) / Time (seconds), also I have to[tex]1hour * \frac{60min}{1hour}*\frac{60s}{1min}\\1h=3600s[/tex]

so, for the lightbulb

[tex]100W= \frac{Energy}{3600s*4}\\Energy=100W*14400s\\ E=1440000J =1440KJ[/tex]

Analogously, for the microwave

[tex]1200W= \frac{Energy}{60s*5}\\Energy=1200W*300s\\ E=360000J =360KJ[/tex]

Now, I have to express the efficiency as Heat energy / power * 100 so[tex]1.8= \frac{Heat Energy}{100W}*100\\Heat Energy=1.8J[/tex]

Done

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